NDS problems

I am having problems with users not being able to get drive mappings when login to the network. They are all part of the same context and have the same rights and login scripts at the container level. This problem does not occur to all users in thatdepartment, but to a few and never the same ones, random. The other problem I have encountered is that some workstations cannot find the tree. You can see the tree from the login screen, but you cannot access a context. Error message posts indicating “cannot find tree”.
We are running Netware 5, using DHCP, Windows NT4 workstations.
We have 4 NDS servers and 2 production servers. Problem comes from one of the production servers only.
I need to know any possible solutions to this issue.