Not Seen In Workgroup?

Have several PC in Workgroup. Same SN MAsk, Same IP scheme, last octet different on each PC running thru hub conected to router then to DSL Modem.

All machines running W2K. One of my machines now suddenly cannot see or be seen on the network. THe change is when I connected this particular PC durectly to the DSL modem and changed the IP scheme to match the modem. Was doing some troubleshooting for CISCO VPN client I was installing.
Now, back on the workgroup, this PC seems not to be recognized by the other machines.
I can ping them all, and they can ping me…but cannot see them.
Help?