Shares, groups, & access denied

On an NT4 Domain Controller I made a global group with 5 users as members, then on a Win2K member server I made a local group that has the Global group as a member. I made a shared folder on the Win2K server, then gave the local group Full Control permissions for the share and NTFS permissions of Modify (everything but Full Control is checked under Advanced), and I checked 'Reset permissions on all child objects and enable propagation of inheritable permissions. On the Domain Controller I resynched the domain. Two of the 5 users were unable to access the share, receiving a "\\servername\blah is not accessible. Access is Denied" error on their NT 4 workstations, which are part of the same domain as the Win2K server. However, if they log on from any other machines in the network, regardless of OS, they are able to access the share. Other members of the global group have no problem, even when they use these two workstations. This is only a problem on these two workstations. I tried Remove workstation from domain, change workstation name, add workstation back to domain - This did not work either. There are no "Deny" flags set under Share Permissions or File Security. These users have the exact same group memberships as another user who is able to access the share from any workstation. Why can't they access the share from their workstations?