Sync issues with ical, mail and .mac

[andrewj475]

I have always maintained 3 macs (2 desktops and a portable) and synced them via .mac. I sync iCal, Safari, Mail.
Since switching all three to Leopard it has all gone haywire. iCal continued to work and sync for a while but now does not appear to sync at all. Mail now displays multiple (six at the last count) non-functioning "on my mac" mailboxes as well as the originals which continue to work fine.
One strange anomaly is that I also sync the calendars on my ipod and Treo and these show a different calendar set altogether than appears on any Mac.
I have reset all three computers in .mac sysprefs. Unregistered and re-registered all three. Trashed the pref files (although only on one of them) At this point I want to find a way to get back to a clean slate but don't know how to proceed. In checking other resources I see that I am not the only one with this problem.
Any suggestions?