Strange startup crash

I have a 64-bit Windows 7 computer. 64-bit Blender versions have stopped working on this computer sometime between revision 51279 (Oct. 12, 2012) and revision 52225 (Nov. 15, 2012). Every non-MinGW 64-bit build from before that period works perfectly, and no 64-bit build has worked since. 32-bit builds, on the other hand, have worked without incident or interruption.

Before just now, all I would ever get was the blender command prompt appearing and then immediately fading to grey, before Windows declared that “a problem has caused this program to stop working” and shut it down.

But now I see this: the command prompt reads this, and writes these two lines in quick succession:

Read new prefs: C:\Users[me]\AppData\Roaming\Blender Foundation\Blender\2.65\config\userpref.blend
Writing C:\Users[me]\AppData\Roaming\Blender Foundation\Blender\2.65\config\startup.crash.txt

It then immediately closes, with no Blender ever opening. I have to try to start Blender multiple times just to read those two lines.

Here are the entire contents of the .txt file referred to:

Blender 2.65 (sub 9), Revision: 54095

Kind of disappointing, considering that I had hoped that it would contain something useful, rather than just the version I was attempting to run, but oh well.

Does anyone at all know what could be causing this? If not, do you know whom I could ask who might know?

Edit: Tested on a second W7 64-bit laptop. 2.66a fails even to write the crash file. Is this common?