Annb, Don't know if this is your problem or not, but this is what I found via goolge.....
Will
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fix for Palm Hot Sync/Verizon Wireless Sync conflict error #16397
Following is a possible fix for a syncing problem with the new Verizon version of the
Treo 650.
The problem occured in my phone AFTER the initial installation of Palm Desktop software and the first sync to the Treo 650. After several syncs, the syncs to "Tasks" and "Calendar," and in my case to the 3rd party Meeting Maker all stopped, and the log specified error #16397.
The fifth call to Palm led to a solution, at least for me. Another user had reported a similar problem and either Palm or Verizon had diagnosed an issue with Wireless Sync, which I have enabled to obtain email. Either VErizon or the user had suggested disabling Wireless Sync.
I couldn't find a way to disable Verizon's program Wireless Sync. But in checking the top menus on the program, going to "Setup," then to "Connection Settings," then to "Advanced" (in the bottom right part of the screen, one will see a check-box in the "Advanced Settings" scren for "Enable oother sync apps." This says "Enabling this may duplicate data." CHECK this box. I did, then clicked "OK" and got out of the Wireless Sync program, then did a HotSync. Worked perfectly. Has worked perfectly ever since.