My XP box had a problem with offline files not synchronizing. I would click on the offline files icon and it would say it had one file that needed to be synchronized. I would synchronize the files and then in a minute it would go back to saying it had one file to synchronize. It would synchronize again when I logged off but it would still have one file needing synchronization. I tried to find the file but everything looked like it was synchronized.
I finally decided to do something drastic. I booted up in safe mode and deleted the CSC subdirectories. I had a couple of Gigabytes in the subdirectories when it should only have been 400 MB. Something was really screwy. There were a couple of files above the subdirectories. I guess I was curious what would happen so I left the files them alone.  When I rebooted everything worked fine. It did take a few minutes to sync the offline files but that was small price to pay to get rid of this annoyance.