I have an app. by illum software - listpro. I made the mistake of making changes in the PC copy of the application and also to the handheld copy of the application.
ActiveSync duly noted that it needed my attention to resolve the conflict. I selected handheld overwrites PC, went and found the file on the PC that it was complaining about and renamed it, hoping that I would wind up with 2 copies of the lists either on the PC or on the handheld.
I let ActiveSync continue, it renamed the file on the handheld to the same name as the copy on the PC and it synchronized the file on the handheld right out of existence! Losing all the changes that I made during my holiday shopping trip yesterday.
A Palm based device would never have had this issue in the first place. PalmOS understands that a file (database) can have updates from two sources and it will try to resolve the conflicts on a record by record basis.
The lesson to take from this experience is - update only on the handheld or only on the PC, if updates must be made in two places - good luck, or sync between update sessions to maximize the chance of updates flowing in the correct direction.