If it's an XP client, run this reg key (copy into file named smb.reg and run on client, I also ran on servers):
REGEDIT4
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\NetBT\Parameters]
"SMBDeviceEnabled"=dword:00000000
It seems to fix a lot of browse issues with XP. But make sure you're pointing your DNS on the WS to the same DNS server your DC uses. This got rid of an annoying "You may not have permission to browse the network" error I persistently got on XP clients.