Not able to login on peer netwwork.

When the ‘offending’ system boots, no login opportunity is presented by Win 98. Other systems on the peer network can see the contents of the ‘offending’ system’s hard drive but the ‘offending’ system can’t see others. Subsequently, after the ‘offending’ system has logged in to an ISP, Windows presents a peer network login screen. After logging in at this point, the ‘offending’ system can browse the peer network. Why doesn’t the peer network login screen appear initially at boot time? (Ofcourse, the ‘offending’ system “used to work” fine up until it started misbehaving.)