I have a new user with Windows mobile 7. He's getting Error 8500201d when trying to sync. I had him uncheck calendar and retry syncing and all sync'd except for Calendar. Re-enabling calendar throws the same error. I've searched the error and discovered having attachments on calendar items could cause the problem. I asked the user if he does this and he informed me he needs his calendar items to have attachments. Is there any other solutions that would allow him to sync calendar and keep attachments on his calendar items?