Classical Samba Issues

I'm running a Samba server on my Gentoo box. When I go to map a drive on this Windows box, I get the evil "The mapped network drive could not be created because the following error has occurred: The specified network name is no longer available". The Windows firewall is disabled. Long story short, Samba worked great on another (quite old) laptop. It was running Windows XP, but did not have SP2. This machine I'm trying to use now is a desktop running Windows XP with SP2. I've read some listings saying that SP2 raises some problems for Samba servers, so I'm guessing there's just some workaround or fix that I just don't know about yet? I came up empty at the Gentoo forums. Anyone know about this?