samba - Mar 1999 - Can't see anymore Unix server from NT PC

Hello Gurus !
     
     I'm having a problem that I don't undestand because it worked great
at
     the beginning.
     
     We have a Unix server Solaris 2.5.1 and a number of Pc stations Win95 
     or NT4.
     
     On my particuliar Pc, I can't see anymore the Unix server through the 
     Explorer: Network neighborhood, Entire Network, Microsoft Windows 
     Network...
     However, I still have the partitions mounted on reboot but I can't 
     mount a new one.
     My configuration is : Win NT4 SP3.
     
     The other PC NT or 95 manage to see it.
     
     Can anyone help me... Is it a problem with encrypted password ?
     Thanks
     
     Isabelle