also about mapping a drive

I’m running a peer to peer network of 20 Win98SE machines. I map network drives of all other machines to one box for backup purposes. One PC that used to be mapped is not mapped anymore, nor can I remap it anymore. The identification is the same andnothing else has changed. It just quit workin’!?! I can see it and access it through Network Neighborhood, but when I try to map a drive to it I get an error “share name not found on running network, blah, blah, blah. It’s running the same protocolsas the others, is in the same workgroup, I just can’t figure this out. Any suggestions? Thanks.