Network Neighborhood not watching

[Alfonso García]

Dear Sirs:

In job I've been using the following servers:
SERVER1 is a NT4.0-SP4 as PDC for one domain,
SERVER2 was a Mandrake 8.0 based box with samba 2.not remember now version, 
sharing some folders for extra disk space for the users (over 200 Windows 
98). This was set up at user security level.
Both were working so fine. From any of the clients, when I clicked on 
Network Neighborhood, I watched a list of all the clients, and both servers.
Last week we had an infection with NIMDA virus. SERVER1 was affected 
seriously, so we decided to duplicate the users from SERVER1 to SERVER2 and 
duplicate the personals shared resources to the equivalents home 
directories. We switched off SERVER1 from the network, and set up SERVER2 
to be at domain security level and accepting logons, changed the name to 
SERVER1, and restarted the samba daemons. Again so fine. The users can log 
on, we were unmo
The problem now is with the clients. If we try to watch the Network 
Neighborhood now we get and error saying that the network is not avalaible. 
What is more curious is that if we write, for example, in the explorer bar 
\\SERVER1 we get again the error pop up message, but, THE SHARED RESOURCES 
ARE SHOWN!!
I don't know how to solve this problem (I'm almost newbie with samba). 
Suggestions??

Thanks in advance!!