qt_scale_image_32bit<Blend_ARGB32_on_ARGB32_SourceAlpha> crashes!

Hello.

I got a bug-report from a user, reporting that my application crashes on one of his systems (Windows XP, Celeron CPU without MMX/SSE only, no SSE2). I sent him Debug symbols and he sent me back a stack trace. The type of the crash is ACCESS VIOLATION and it always crashed in the function "qt_scale_image_32bit<Blend_ARGB32_on_ARGB32_SourceAlpha>". Note that I cannot reproduce the crash myself, but the user says he can reproduce it very reliably!

Just to be sure that this is NOT a bug in my own code, I created a very simple test application (just one dialog with a few widgets). Still the user says the test app crashes on his systems reproducible! He says it can be triggered, for example, by opening the font selection combobox (QFontComboBox). That is in the simple test app. In my original app there was no QFontComboBox at all. So this is NOT specific to QFontComboBox, but a more general issue.

One more interesting fact: The users says it only happens when he sets the Windows color-depth to 24-Bit or 32-Bit, but it runs fine with 16-Bit. So this might give a hint on what causes the crash in Qt code.

My example app code is here:
http://www.mediafire.com/file/lcr2hesh47y2f95/QtTestApp.2013-03-03.tar.bz2

For what it's worth, a binary (Win32) is provided too:
http://www.mediafire.com/file/xbm3bmgozyedg9r/QtTestApp.2013-03-03.7z

The crash report (call stack) I got from the user is here:
http://pastie.org/private/iccugicw0bormqk0daqjhq

Other crash report (call stack) from my original program looks like this:
http://pastie.org/private/zbsiyaqp7ivd0jeqbs7fxg

If you need any more info, please let my know and I'll forward it...

Regards,
MuldeR