master browser problem on XP home net

I have a small XP SP2 home network with a router that worked fine for two
years, but now my two computers cannot see each other (although they both
see the internet fine). Using Net View I get system error 6118 on one
computer; the other gives a normal response. Browstat sta produces the
message that "browsing is not active on the domain" on the same computer
with the 6118 problem. In my event log I have errors 8021 and 8032
regarding the master browser. As a probably related issue, my Share
documents folder on the problem box is only available from the Administrator
account no matter how many times I set it to share.

I have tried everything I could understand in MSKB article #135404 and a
whole bunch of others to no avail. Uninstalled firewall (zonealarm),
stopped and started the computer browsing service, the tcp/ip service, etc.

I would appreciate any help. I am back to sneaker net.

Greg