ICal "No such entity error"

I maintain my personal calendars on 2 different Macs. 1 is a MacBook Pro. The other is a Desktop G4 system. Both are maintained with the most current version of OSX (10.4.9), and have been running it for some time, its not a new upgrade.

Typically, several times a day I update the calendar with the desktp synching to .Mac. Then in the evening, I synch with the MacBook Pro. This has gone for a long time with no problems.

Several days ago, I did synch twice with the desktop just fine. Then I synched to pick up the changes on the MacBook Pro. Then a new event needed to be added to the calendar which I did with the desktop and then synched and suddenly I get these messages...

quote...

[NOTE: this exception originated in the server.]
No such entity named com.apple.palm.calendars.Category
<<<end quote.

An the calendar would not synch.

The desktop has never had a Palm connected to it. The MacBook Pro does, but only using the Palm synch system and not iSych or, and never has ever tried to synch into the calendar or addressbook of the MacOS or use the Mac OS synch system for it. And I had not even used the palm to do any synch for more than a week previous.

I have run permission. No problem listed. I have run Diskwarrioer, no problems listed.

I have tried to tell .Mac to reset and take all info from the desktop, but I still get this error and it fails to do that....or, the other direction, and still the same failure.

Any way to clean this up? The problem is ONLY on the desktop G4, the MacBookPro continues to synch just fine.

Thanks, William