No... but I think I found the problem. The apple support site had a page
http://support.apple.com/kb/HT2292, "Using MSCONFIG to troubleshoot conflicts in Windows Vista and Windows 7". It states, "In Windows Vista and Windows 7, some background processes can cause issues for other programs and processes. These conflicts can prevent applications such as iTunes and QuickTime Player from working correctly, opening, or even installing. You might be able to resolve these conflicts by disabling some items using the System Configuration Utility (MSCONFIG) in Windows."
I've gone through the steps and re-enabled most of the services and start up items and QuickTime still works. There are a few that remain, I don't really care about them... I'll run it like this for a week, then I'll enable the rest to see which one if any is causing the conflict.
The article makes the most sense of anything I can see.
Reinstalling GTK after the problem showed up was not a solution... it just allowed me to run QuickTime for the current boot. 🙂