Wow, it’s been a long time since I’ve posted here! =P
Anyway, I just stumbled upon this fix for iTunes crashing almost immediately after launch on Windows 8.1 (might be triggered by launching the iTunes Store?), from a discussion board post on Apple Support Communities by MarkJaco:
I had this issue. Try copying QTWinMovie.dll from c:\program files (x86)\common files\apple\apple application support to c:\program files (x86)\iTunes. This solution fixed it for me and was easy!
Hopefully this will help you out as well! =)