I'm having the same problem.
I'm running the latest Windows 7 and itunes and apple software. Whenever I try to sync with iTunes, it gets up to Step 3 of 4 and itunes crashes/freezes and then I have to shut it down.
I have then tried to find my apps and a lot of them seem to have disappeared. When go to download them they say they are installed. When I search for them they appear.
The message says that Windows is searching for a solution but nothing has appeared.
I've tried removing and reloading iTunes. I've tried creating a new account and transferring purchases, syncing and starting again. I get to the last step and iTunes crash.