PC’s cannot share files under Windows 95

I am running a 50 user NT4 Network, with Windows 95 clients. 5 of the clients will not share drives. When I try to assign a share, and give The World full Access, the Error Message comes back saying “You cannot view the list of users at this time. Please try later.” All the network properties are identical to the other 45 clients, with user level access control, on the same NT Domain and they work. Technet suggests a problem with the mapi32.dll, but I have replaced this, with no success.