Do a clean install. Choose to run the installer as Administrator, both CD's. Patch the game, run choosing to run as Administrator. Run the game, choose to run as administrator.
Do not install any add-ons.
See if you still have the problem.
The biggest thing, is it seems installing anything that is going to access a USB device, TrackIR, CH, Cougar, LOMAC, most games, most programs... hell it seems everything... needs to be run as Admin in Vista.
Just an FYI, I run 1.12a in Vista without any issues. I use 1.12a because 1.12b wasnt out yet, and I just installed the SF updated drivers for Vista. And since its working no need to reinstall.