It hangs there? Most probably it says "Waiting to Sync", or "Pending synchronization" or something similar and doesn't start actually syncing? Or if it starts to sync, it does it one time for no apparent reason, and then again stops, saying pending next time?
Been there, had that. I had that starting early Vista days. Was looking for the answer in the whole wide web for quite some time to no avail. The only advise from me is, if you have any kind of Microsoft support agreement, turn to it.
If someone answers this question here, then I'm all ears. I'm subscribing to this thread. If you find an answer, post it. I will definitely read it. If noone answers this in couple of weeks or a month, you can pick my advise to turn to Microsoft as an answer. :)