I've never had this problem but an educated guess would suggest it keeps returning you to the account page because you have no contacts it has synced, so therefore its empty?
To further diagnose this problem, could you provide a few more details?
Which way did you do the sync? I.e.: did you have your iPhone all set up with contacts etc but not on your computer and not on MobileMe BEFORE you had MobileMe? If it is this one I'm not sure the iPhone syncs up first, I believe (correct me people if I'm wrong) on the initial set up sync it will only download from MobileMe? Meaning if MobileMe is empty but your iPhone isn't, your iPhone will lose its contacts.
Did you have all your contacts stored on your computer which then synced over to the iPhone when it was plugged in? This would be the ideal set up, so when you had MobileMe, the computer would then sync up to MobileMe all your contacts and calendar etc, which would then download to the iPhone once finished. MobileMe syncing obviously disables the iTunes contact/calendar syncing. If this is what you did and it still wasn't working I'm not sure what went wrong. When syncing MobileMe via your computer you should have been given an option to "MERGE" data on your computer and MobileMe, "REPLACE" all data on MobileMe with data FROM your computer or "REPLACE" all data on the computer with data FROM MobileMe. As a new user you would have been best to selected "REPLACE ALL DATA ON MOBILE ME WITH DATA ON MY COMPUTER", otherwise you may lose data on your computer. This is just for the initial sync, once this is done all connected devices will operate a 2-way push sync service.
Hope this helps and doesn't confuse or patronize in any way!