I have this problem (maybe almost) every time I close the wallet (FILE/EXIT).
Both regular and testnet version, different PCes, different Win (7/8), all x64.
Sometimes I have to kill the process, because it still resides in the process list
and the icon stays in systray. Here is what the error looks like with the test wallet:

Problem signature:
  Problem Event Name: APPCRASH
  Application Name: spreadcoin-qt.exe
  Application Version: 0.9.15.4
  Application Timestamp: 52cf3800
  Fault Module Name: spreadcoin-qt.exe
  Fault Module Version: 0.9.15.4
  Fault Module Timestamp: 52cf3800
  Exception Code: c0000005
  Exception Offset: 00d9b9cf
  OS Version: 6.1.7601.2.1.0.256.48
  Locale ID: 1033
  Additional Information 1: 0a9e
  Additional Information 2: 0a9e372d3b4ad19135b953a78882e789
  Additional Information 3: 0a9e
  Additional Information 4: 0a9e372d3b4ad19135b953a78882e789

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EDIT:For some reason IMG code doesn't work...
http://i.imgur.com/8Pc0R76.png