As usual I had Bitcoin-Qt (v0.9, Win 7 x64) running in the background and sent a transaction via RPC, about 10 minutes later an exception was thrown, ultimately leading to a corrupted wallet.dat file. At that very moment no action was performed and to my best knowledge no other program than bitcoin-qt.exe had access to the wallet.dat. The event logs don't show any incident besides this one during that time.
Screenshots:

debug.log:
2014-04-01 23:02:46 AddToWallet 763f6e7d66a4b44bd1c6f7c566a98c8fe9465e00e2a048e046f38566f2fbe9fd new
2014-04-01 23:02:46 AddToWallet 763f6e7d66a4b44bd1c6f7c566a98c8fe9465e00e2a048e046f38566f2fbe9fd
...
2014-04-01 23:11:54 socket recv error 10054
2014-04-01 23:12:38 UpdateTip: new best=000000000000000090b4ce53f41be9c3af7d2b9220a6585926b8fcab59e78457 height=293646 log2_work=77.684919 tx=36044176 date=2014-04-01 23:11:43 progress=0.999997
2014-04-01 23:12:38 ProcessBlock: ACCEPTED
2014-04-01 23:12:40 AddToWallet 763f6e7d66a4b44bd1c6f7c566a98c8fe9465e00e2a048e046f38566f2fbe9fd update
2014-04-01 23:12:40 *** System error: CDB() : can't open database file wallet.dat, error 2
2014-04-01 23:12:44 ERROR: ProcessBlock() : AcceptBlock FAILED
2014-04-01 23:12:44 Requesting shutdown
2014-04-01 23:12:44 Running Shutdown in thread
2014-04-01 23:12:44 opencon thread interrupt
2014-04-01 23:12:44 dumpaddr thread stop
2014-04-01 23:12:44 msghand thread interrupt
2014-04-01 23:12:44 addcon thread interrupt
2014-04-01 23:12:44 net thread interrupt
2014-04-01 23:12:44 Shutdown : In progress...
2014-04-01 23:12:44 StopNode()
2014-04-01 23:12:45 UPNP_DeletePortMapping() returned : 0
2014-04-01 23:12:45 upnp thread interrupt
2014-04-01 23:12:45
************************
EXCEPTION: St13runtime_error
CDB() : can't open database file wallet.dat, error 2
E:\Bitcoin-0.9.0\bitcoin-qt.exe in Runaway exception
Requesting initialize
Running AppInit2 in thread
2014-04-01 23:15:37
....
2014-04-01 23:17:22 Bitcoin version v0.9.0.0-g92d25e4-beta (Sun, 16 Mar 2014 11:05:28 +0100)
2014-04-01 23:17:22 Using OpenSSL version OpenSSL 1.0.1e 11 Feb 2013
2014-04-01 23:17:22 Default data directory C:\Users\uname\AppData\Roaming\Bitcoin
2014-04-01 23:17:22 Using data directory E:\Bitcoin-0.9.0\Data
2014-04-01 23:17:22 Using at most 125 connections (2048 file descriptors available)
2014-04-01 23:17:22 Using 4 threads for script verification
2014-04-01 23:17:22 Using wallet wallet.dat
2014-04-01 23:17:22 init message: Verifying wallet...
2014-04-01 23:17:22 dbenv.open LogDir=E:\Bitcoin-0.9.0\Data\database ErrorFile=E:\Bitcoin-0.9.0\Data\db.log
2014-04-01 23:17:23 Renamed wallet.dat to wallet.1396394242.bak
2014-04-01 23:17:23 Error: Salvage found errors, all data may not be recoverable.
2014-04-01 23:17:23 Salvage(aggressive) found no records in wallet.1396394242.bak.
2014-04-01 23:20:15 Initialization result: 0
2014-04-01 23:20:15 Requesting shutdown
2014-04-01 23:20:15 Running Shutdown in thread
2014-04-01 23:20:15 Shutdown : In progress...
2014-04-01 23:20:15 StopNode()
2014-04-01 23:20:15 Shutdown : done
2014-04-01 23:20:15 Shutdown finished
2014-04-01 23:20:15 Shutdown result: 1
2014-04-01 23:20:15 Stopping thread
2014-04-01 23:20:15 Stopped thread
Requesting initialize
Running AppInit2 in thread
2014-04-01 23:31:51
db.log:
wallet.dat: unable to flush: No such file or directory
txn_checkpoint: failed to flush the buffer cache: No such file or directory
wallet.dat: No such file or directory
wallet.dat: No such file or directory
file unknown has LSN 1/59393, past end of log at 1/28
Commonly caused by moving a database from one database environment
to another without clearing the database LSNs, or by removing all of
the log files from a database environment
Page 0: metadata page corrupted
Page 0: could not check metadata page
wallet.dat: DB_VERIFY_BAD: Database verification failed
file unknown has LSN 1/59393, past end of log at 1/1076
Commonly caused by moving a database from one database environment
to another without clearing the database LSNs, or by removing all of
the log files from a database environment
wallet.1396394242.bak: DB_VERIFY_BAD: Database verification failed
file unknown has LSN 1/59393, past end of log at 1/1076
Commonly caused by moving a database from one database environment
to another without clearing the database LSNs, or by removing all of
the log files from a database environment
file unknown has LSN 1/59393, past end of log at 1/1076
Commonly caused by moving a database from one database environment
to another without clearing the database LSNs, or by removing all of
the log files from a database environment
file unknown has LSN 1/59393, past end of log at 1/1076
Commonly caused by moving a database from one database environment
to another without clearing the database LSNs, or by removing all of
the log files from a database environment
file unknown has LSN 1/59393, past end of log at 1/1076
Commonly caused by moving a database from one database environment
to another without clearing the database LSNs, or by removing all of
the log files from a database environment
System events:
<Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">
<System>
<Provider Name="Application Error" />
<EventID Qualifiers="0">1000</EventID>
<Level>2</Level>
<Task>100</Task>
<Keywords>0x80000000000000</Keywords>
<TimeCreated SystemTime="2014-04-01T23:13:53.000000000Z" />
<EventRecordID>126257</EventRecordID>
<Channel>Application</Channel>
<Computer>uname</Computer>
<Security />
</System>
<EventData>
<Data>bitcoin-qt.exe</Data>
<Data>0.9.0.0</Data>
<Data>51a93980</Data>
<Data>bitcoin-qt.exe</Data>
<Data>0.9.0.0</Data>
<Data>51a93980</Data>
<Data>c0000005</Data>
<Data>0000000000a28884</Data>
<Data>1374</Data>
<Data>01cf4df2e8d7d14e</Data>
<Data>E:\Bitcoin-0.9.0\bitcoin-qt.exe</Data>
<Data>E:\Bitcoin-0.9.0\bitcoin-qt.exe</Data>
<Data>4a2d0955-b9f3-11e3-bb66-002522d18708</Data>
</EventData>
</Event>
<Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">
<System>
<Provider Name="Windows Error Reporting" />
<EventID Qualifiers="0">1001</EventID>
<Level>4</Level>
<Task>0</Task>
<Keywords>0x80000000000000</Keywords>
<TimeCreated SystemTime="2014-04-01T23:14:24.000000000Z" />
<EventRecordID>126258</EventRecordID>
<Channel>Application</Channel>
<Computer>uname</Computer>
<Security />
</System>
<EventData>
<Data>15393675</Data>
<Data>20</Data>
<Data>APPCRASH</Data>
<Data>Nicht verfügbar</Data>
<Data>0</Data>
<Data>bitcoin-qt.exe</Data>
<Data>0.9.0.0</Data>
<Data>51a93980</Data>
<Data>bitcoin-qt.exe</Data>
<Data>0.9.0.0</Data>
<Data>51a93980</Data>
<Data>c0000005</Data>
<Data>0000000000a28884</Data>
<Data />
<Data />
<Data>C:\Users\uname\AppData\Local\Temp\WERFD28.tmp.WERInternalMetadata.xml</Data>
<Data>C:\Users\uname\AppData\Local\Microsoft\Windows\WER\ReportArchive\AppCrash_bitcoin-qt.exe_5418e4c31125a14228975943264c24c5ae049d_771274c7</Data>
<Data />
<Data>0</Data>
<Data>4a2d0955-b9f3-11e3-bb66-002522d18708</Data>
<Data>0</Data>
</EventData>
</Event>
Windows error report:
Version=1
EventType=APPCRASH
EventTime=130408676335983948
ReportType=2
Consent=1
UploadTime=130408676337754049
ReportIdentifier=4a2d0956-b9f3-11e3-bb66-002522d18708
IntegratorReportIdentifier=4a2d0955-b9f3-11e3-bb66-002522d18708
Response.BucketId=15393675
Response.BucketTable=20
Response.type=4
Sig[0].Name=Anwendungsname
Sig[0].Value=bitcoin-qt.exe
Sig[1].Name=Anwendungsversion
Sig[1].Value=0.9.0.0
Sig[2].Name=Anwendungszeitstempel
Sig[2].Value=51a93980
Sig[3].Name=Fehlermodulname
Sig[3].Value=bitcoin-qt.exe
Sig[4].Name=Fehlermodulversion
Sig[4].Value=0.9.0.0
Sig[5].Name=Fehlermodulzeitstempel
Sig[5].Value=51a93980
Sig[6].Name=Ausnahmecode
Sig[6].Value=c0000005
Sig[7].Name=Ausnahmeoffset
Sig[7].Value=0000000000a28884
DynamicSig[1].Name=Betriebsystemversion
DynamicSig[1].Value=6.1.7601.2.1.0.256.48
DynamicSig[2].Name=Gebietsschema-ID
DynamicSig[2].Value=1031
DynamicSig[22].Name=Zusatzinformation 1
DynamicSig[22].Value=2424
DynamicSig[23].Name=Zusatzinformation 2
DynamicSig[23].Value=2424212a5196a04dd7c8ce2b9d9782d7
DynamicSig[24].Name=Zusatzinformation 3
DynamicSig[24].Value=3a7e
DynamicSig[25].Name=Zusatzinformation 4
DynamicSig[25].Value=3a7e278a7e89fc74f9d32b4b23228af3
UI[2]=E:\Bitcoin-0.9.0\bitcoin-qt.exe
UI[3]=bitcoin-qt.exe funktioniert nicht mehr
UI[4]=Windows kann online nach einer Lösung für das Problem suchen.
UI[5]=Online nach einer Lösung suchen und das Programm schließen
UI[6]=Später online nach einer Lösung suchen und das Programm schließen
UI[7]=Programm schließen
LoadedModule[0]=E:\Bitcoin-0.9.0\bitcoin-qt.exe
LoadedModule[1]=C:\Windows\SYSTEM32\ntdll.dll
LoadedModule[2]=C:\Windows\system32\kernel32.dll
LoadedModule[3]=C:\Windows\system32\KERNELBASE.dll
LoadedModule[4]=C:\Windows\system32\ADVAPI32.dll
LoadedModule[5]=C:\Windows\system32\msvcrt.dll
LoadedModule[6]=C:\Windows\SYSTEM32\sechost.dll
LoadedModule[7]=C:\Windows\system32\RPCRT4.dll
LoadedModule[8]=C:\Windows\system32\CRYPT32.dll
LoadedModule[9]=C:\Windows\system32\MSASN1.dll
LoadedModule[10]=C:\Windows\system32\GDI32.dll
LoadedModule[11]=C:\Windows\system32\USER32.dll
LoadedModule[12]=C:\Windows\system32\LPK.dll
LoadedModule[13]=C:\Windows\system32\USP10.dll
LoadedModule[14]=C:\Windows\system32\IMM32.dll
LoadedModule[15]=C:\Windows\system32\MSCTF.dll
LoadedModule[16]=C:\Windows\system32\IPHLPAPI.DLL
LoadedModule[17]=C:\Windows\system32\NSI.dll
LoadedModule[18]=C:\Windows\system32\WINNSI.DLL
LoadedModule[19]=C:\Windows\system32\MSWSOCK.dll
LoadedModule[20]=C:\Windows\system32\WS2_32.dll
LoadedModule[21]=C:\Windows\system32\ole32.dll
LoadedModule[22]=C:\Windows\system32\OLEAUT32.dll
LoadedModule[23]=C:\Windows\system32\SHELL32.dll
LoadedModule[24]=C:\Windows\system32\SHLWAPI.dll
LoadedModule[25]=C:\Windows\system32\WINMM.dll
LoadedModule[26]=C:\Windows\system32\CRYPTSP.dll
LoadedModule[27]=C:\Windows\system32\rsaenh.dll
LoadedModule[28]=C:\Windows\system32\CRYPTBASE.dll
LoadedModule[29]=C:\Windows\system32\uxtheme.dll
LoadedModule[30]=C:\Windows\system32\dwmapi.dll
LoadedModule[31]=C:\Windows\system32\profapi.dll
LoadedModule[32]=C:\Windows\System32\wship6.dll
LoadedModule[33]=C:\Windows\System32\wshtcpip.dll
LoadedModule[34]=C:\Windows\system32\ntmarta.dll
LoadedModule[35]=C:\Windows\system32\WLDAP32.dll
LoadedModule[36]=C:\Windows\system32\pcwum.dll
LoadedModule[37]=C:\Windows\system32\mscoree.dll
LoadedModule[38]=C:\Windows\Microsoft.NET\Framework64\v4.0.30319\mscoreei.dll
LoadedModule[39]=C:\Windows\Microsoft.NET\Framework64\v4.0.30319\perfcounter.dll
LoadedModule[40]=C:\Windows\system32\pdh.dll
LoadedModule[41]=C:\Windows\system32\MSVCR110_CLR0400.dll
LoadedModule[42]=C:\Windows\system32\aspnet_counters.dll
LoadedModule[43]=C:\Windows\Microsoft.NET\Framework64\v4.0.30319\aspnet_perf.dll
LoadedModule[44]=C:\Windows\system32\MSVCR100.dll
LoadedModule[45]=C:\Windows\WinSxS\amd64_microsoft.vc80.crt_1fc8b3b9a1e18e3b_8.0.50727.6195_none_88e41e092fab0294\MSVCR80.dll
LoadedModule[46]=C:\Program Files\Microsoft SQL Server\100\Shared\instapi10.dll
LoadedModule[47]=C:\Program Files\Microsoft SQL Server\110\Shared\instapi110.dll
LoadedModule[48]=C:\Windows\system32\CFGMGR32.dll
LoadedModule[49]=C:\Windows\system32\NLAapi.dll
LoadedModule[50]=C:\Windows\system32\napinsp.dll
LoadedModule[51]=C:\Windows\system32\pnrpnsp.dll
LoadedModule[52]=C:\Windows\system32\DNSAPI.dll
LoadedModule[53]=C:\Windows\System32\winrnr.dll
LoadedModule[54]=C:\Windows\system32\rasadhlp.dll
LoadedModule[55]=C:\Windows\System32\fwpuclnt.dll
LoadedModule[56]=C:\Windows\system32\dhcpcsvc6.DLL
LoadedModule[57]=C:\Windows\system32\dhcpcsvc.DLL
LoadedModule[58]=C:\Windows\system32\RpcRtRemote.dll
LoadedModule[59]=C:\Windows\system32\CLBCatQ.DLL
State[0].Key=Transport.DoneStage1
State[0].Value=1
State[1].Key=DataRequest
State[1].Value=Bucket=15393675/nBucketTable=20/nResponse=1/n
FriendlyEventName=Nicht mehr funktionsfähig
ConsentKey=APPCRASH
AppName=bitcoin-qt.exe
AppPath=E:\Bitcoin-0.9.0\bitcoin-qt.exe