Inkscape will not launch (WIndows 7, 64-bit)

I have regularly used Inkspace without problems in the past. Now, sometimes when I try to launch it, get this message "Inkscape has stopped working" (details pasted below). If have uninstalled and reinstalled, rebooted, etc. It's possible that this change coincided with installation of Firefox 4 beta 12, or installion of Windows 7 service pack 1.

I get error code 0xc0000005 which apparently relates to memory problems. I ran the memory-checking software memtest86+, but it did not return any problems (I ran tests through 17 iterations).

Problem signature:
  Problem Event Name: APPCRASH
  Application Name: inkscape.exe
  Application Version: 0.47.0.9
  Application Timestamp: 4c691d0c
  Fault Module Name: StackHash_4c0d
  Fault Module Version: 0.0.0.0
  Fault Module Timestamp: 00000000
  Exception Code: c0000005
  Exception Offset: 8fd70000
  OS Version: 6.1.7601.2.1.0.256.48
  Locale ID: 1033
  Additional Information 1: 4c0d
  Additional Information 2: 4c0d4d78887f76d971d5d00f1f20a433
  Additional Information 3: 4c0d
  Additional Information 4: 4c0d4d78887f76d971d5d00f1f20a433