I have had my XV6600 for some time now, and have not had any issues with ActiveSync until recently. I am using 4.2 at the moment, although I also tried 4.5 with similar results. Here is the issue.. I plug my phone into the cradle, AS starts up, reports "Looking for Changes" then "Connected" and shows some number of "Items not synchronized." All appears normal. Then, a message box pops up saying "Synchronization cannot be completed successfully." AS shows "Connected" and "Synchronization error." I can still explore the phone, including my 2GB SD memory card, and I can manually drag and drop files between the phone and Windows desktop. But, I cannot sync. I am running XP Pro SP2. I have tried all of the suggestions I have located in this forum to no avail. I am having a similar problem with my i730, and my i700. If I start XP in Safe Mode with networking enabled, and disable my Firewall and AV software, I get the same results. Could there be a Windows service that is not running, or a service that is interfering with AS? Any suggestions would be most appreciated.

If your data is backed up in your computer from previous sync and not much has changed... just do a hard reset and update to Active Sync 4.5. Just be aware that if you have database data it will no longer sync.