Some random thoughts:
- does zeserver have any different eggs in python path than clients? I mean, are they using the same eggs or some differ?
- can you print current time in both client and server and see if they differ in some way? (check also timezone)
- can you post zope.conf from each client and zeo.conf from the server?
- did you read this? Problems with zodb transactions: Client has seen newer transactions than server