VistaPC can't 'see' XpPC

I have a small home network with 1 XP PC, 1 XP laptop and one (new) Vista laptop (sp1). The Two XP machines (sp3) can share files through shared folders. All three machines have an account with the same name and password, file sharing is turned on, I’ve used the stealth ports wizard to allow communications b/w the machines on -10 (local network). The XP machines can connect to a shared folder on the Vista machine. HOWEVER, the Vista machine cannot access shared folders on the XP machines. I get access denied errors, or am told the host name can’t be found or is incorrect. I even added a custom rule to the Vista Comodo instance allowing all tcp/udp traffic between it and any machine on the above IP pool. I added a second rule allowing such traffic with each individual host (using host name). The only way I get the Vista machine to connect to the shared folder on the XP machine is to manually set Defense + Sec and Firewall Sec Levels to disabled, map or connct to the XP machine, and then reenable Comodo. Windows firewall is off.

Any ideas are welcome.