Profile sychronization access denied

I have run into a problem with our Windows 2000 network, running XP Pro clients. I have two users who try to log in from their home machines, and they get the following error msg. ‘Errors occured whil windows was sychronizing your data: offline file [\\domainserver\users on domainserver]: unable to merge offline changes on [\\domainserver\users] Access Denied’. This doesn’t happen when logging in on other machines. There is also an error msg that refers to ‘windows has detectec caching for offline files is turned on’. I have checked security policies and file access permissions for the users and nothing seems wrong. Any ideas about a solution?