Wirelessly posted (8820)
Look at contacts in outlook in the view that shows in a spreadsheed format of rows and columns. Look for empty rows, or any type of oddity that stands out. Delete empty rows and edit as needed, then sync.
If you still have trouble, the other possibility is that contacts database on the device is corrupted. One thing to try is to use the advanced feature of the desktop manager backup utility to clear it, then re-sync.
Also look at the log viewable from desktop manager for clues.