Windows 7: Cannot Connect Win 7 to Workgroup Devices

I have a home network set up in XP as a workgroup with two XP-Pro PCs, one MAC Leopard and one XP-Home. I also have a NAS, a network printer and a printer connected to the MAC and shared on the network.

I set up a new Win 7 PC and it worked on the network for a few days. I have installed a number of programs and updates over the last few days and when I tried to access the network to transfer some data I discovered that somewhere along the way I lost connectivity to most of the other devices on the network. I can still access the NAS and both of the printers but not the other computers.



When I checked out the the Win 7 machine System it still shows that it is a member of the Workgroup.

Any help would be appreciated.