Strange Errors in XP Workgroup access

I have two machines PIII runing XP PRO. One was a member
of the Company Domain the other just a workgroup computer.
I had set up a share on the Company Domain machine and was
able to access it from the workgroup unit. Now to the
problem. I installed a cable modem behind a firewall and
changed the systems over with New IP address new workgroup
names and on the once Domain attached machine a new name.
rebooted a few times. Now I can see both machines in the
windows workgroup but I can only get to the shares from
the original workgroup machine. I set up both machines
with the same user names and passwords. Howerver if I
click on the Old domain attached machine I get a username
and password but then a failure to connect. Tried it by ip
same thing. Also I tried it with a use differnet name
option under networking same problem. Tried resetting the
shares same thing. Has anyone got any ideas how to fix
this.
I turned on just about all services checked the netbios
settings in TCP/IP .... Help.
Does anyone have a util to check rights on a machine?
Is there a way to add a user from one machine to the other
like trusted domains... ?
Thank you in advance for your thoughts.
GMB

Strange Errors in XP Workgroup access