Networking problems

I have a home network setup (MSHOME), without a domain. There are 5 computers
on the network. All can access the Internet through my router. 4 of the
computers are visible when I click on "View workgroup computers". However,
there is 1 system that stubbornly refuses to show up. I re-set up the system
using the network disk created on 1 of the other machines, checked to make
sure the Windows firewall was off. From the problem computer, i can ping
other machines with no problem, but I can't ping the problem system from the
other machines. I'm at my wit's end on this one. I've tried everything I can
think of. The TCP/IP settings seem OK, etc., etc., HELP!!!!!!!