NW65SP8, Novell client 491sp5,win xp sp3

some users, not all, experiencing issues w/ ndps printers going "unavailable" at workstation; seems to randomly change to ready and back to unavailable over and over; seems to affect all ndps printers but not local or tcpip devices; as test, setup ms tcpip printer object for same physical printer represented as ndps printer object also - tcpip consistently stays ready yet ndps equiv jumps to unavailable, etc; at server, ndps object stays appropriately idle; does not impact all users though...any suggestions?