I am replacing my Mac Pro (Snow Leopard) with a Mac Pro with Lion (OS 10.7.5) and my Windows PCs (Windows XP, Windows 7, Windows 8) are not able to connect to the shared folders on the newer Mac Pro. They had no problem connecting to the older Mac Pro. I have gone through all the steps and tried to keep things as simple as possible - everyone is on the "WORKGROUP" workgroup. The 2 Mac users are simple-short names with simple passwords -- AND they work fine on the Mac. There is no Firewall on any Windows PC. Whenever I try to connect with the Windows PCs, I get the window that prompts me for a user and password. No matter what combination I use, I can't get beyond that. I have checked SMB on the Mac.
Is there a firewall I need to turn off on the Mac Pro?
Could this be related in any way to my AT&T router?
Years ago, I changed the IP range to 204.1.1.X.