I've seen following problem twice.
NOWS SBE 2.5 with samba running on vmware workstation (eval version, not patched)
Vista client with novell client from SBE installed.

New user with same name and pw as defined at sbs administrator.
Samba share of one directory (via iManager) - no access problem.
Adding a second share (via iManager) - no problem.

When mapping a network drive letter in vista (or xp) explorer to the share
(share name is LINUX_DATA_LUKASYS)
I see something like connection will be checked and workstation shows
"blue screen".

Windows network drive letter was free - no used before.