Missing Drive Letters

Am running an NT network. NT Servers and all NT clients. Using roaming profiles.

Several users are having problems viewing drives (local and network).All network drives are mapped by logon script except the home drive which is set by profile. Logon script is working

For example:
One user can only see the C: drive from explorer. Go to map a drive and the drives are all there in the drive letter list.
From MSWord/File/Open the only drive visible is a network drive (not even C:)
From a command line all drives can be accessed.

Any ideas??