iTunes freezes on video playback

I am running iTunes v. 11.0.1.12 along with Quicktime V. 7.7.3 (1680.64) on a Windows 7 Pro machine. A few weeks ago I noticed that iTunes will freeze up anytime I try to play a video, forcing me to quit the program using the Task Manager. The same videos play fine in Quicktime. I have tried the following:

• Completely uninstalling iTunes, Quicktime, Bonjour, etc. and reinstalling per http://support.apple.com/kb/HT1923. No effect.
• Launching iTunes in safe mode per http://support.apple.com/kb/TS3430. This worked. I could play the videos in safe mode, but when I attempted to follow the rest of the directions, I could not find any plug-ins to disable. There are none in the listed folders.

Currently, I am using iTunes to locate my videos, right-clicking and selecting "Show in windows explorer" and then opening them in Quicktime. Not an ideal solution at all!

Previously, everything was working normally, so I am at a loss as to what changed. At the time I first noticed the problem I was running iTunes v. 10.7.0.21 along with Quicktime V. 7.7.2 (1680.56). I was hoping the upgrade to iTunes 11 would correct the problem, but no luck.

Any advice would be greatly appreciated.