Can't get computer back on LAn

Once upon a time I had two computers connected to a hub and the hub
connected to my DSL line. For a long time I was able to use either
computer on the DSL line as well as see each computer on the LAN so I
could copy files back and forth. Last week there was a long automatic
update, (Think from Microsoft) that ran and now I can still get on the
DSL line with both computers but can only see one computer on the LAN.
I can see all the files on the one computer on the LAN but I cannot
even see the other computer on the LAN. I have tried reinstalling XP
Business and went through duplicating what the other computer set ups
are but can't get the one computer on the LAN. Went through the
network setup wizard dozens of time. When I try and do a repair on the
network I get an error saying. "Following action cannot be completed-
clearing
NETBT" see your network manager. Any ideas would help.
TonySper