I am absolutely hating iTunes beta on Windows. I hope they get it stable before release.
The iTunes beta is dangerous ... caused me plenty frustration. When you install the beta over 10.3 it changes the backups you have on your system. After I reverted back to 4.3.3 on my iPad iTunes could not restore my back-ups. When I then un-installed iTunes 10.5 beta and re-installed iTunes 10.3 the back-ups couldn't be restored because the beta version changed it and iTunes 10.3 could not read it. So, lesson learned: copy the full iTunes folder over to another drive before installing iTunes beta. You will have to copy it back if you want to revert to iOS 4.3.3 and/or iTunes 10.3.