On sync, only get option to restore.

My gf has been having funny issues syncing/ backing up her iPhone 4. Recently when she plugged her phone in to sync for the first time in a few weeks, iTunes wouldn't recognize the phone at all. We rebooted the phone and the computer and then it recognized the phone and synced and backed fine. A few days later during a sync iTunes froze. We rebooted the computer and itunes and when the iPhone was connected we were only given the option to retore from a back-up or set up as a new phone. We restored from the back up and for a few days phone seemed fine. Then on the next sync, iTunes removed all the apps from her iPhone (but not personal settings so it wasn't a factory restore.) She began to manually add apps back, iTunes froze as she was adding the apps and so she disconneted the phone and restarted her computer. The next time the phone was connected, we were once again presented with the option to only restore from a back-up or set up as a new phone.

To me it sounds like an iTunes issue, and one created by iTunes crapping out during critical parts of backing up or syncing or restoring. She's running it on a PC with Windows 7. It's possible that she updated iTunes between syncs and back-ups so i'm not sure if thsi could be a culprit.

Perhaps one attempt would be to uninstall and reinstall iTunes, but we have had some issues on her machine with that too.

ANybody else had or heard of this problem or have any other suggestions?

thanks