Yes, I've run SFC /scannow a zillion times.
The problem cannot be my network router as my two XP machines see each other just fine and a friend's Vista machine can see the XP machines as well. My router was not touched.
DNS service on my machine is started and generates no errors. I am convinced it's the TCP/IP Helper service that will not start, I can't determine the crux of the problem other than a error 1075 it gives. The only dependency listed is Windows Ancilliary Function Driver. When I look in Device Manager-Hidden Devices this AFD device is listed under non-plug and play devices with no errors so I hoping for some new ideas. I'm looking at registry entries for AFD, Netbt Netbios, LanManager Server and Workstation.
I've edited the LMHOSTA.SAM file to link the computer name to the stations IP address. Have since removed it when it didn't work.
I did look at Hosts and found only the following line was NOT commented out:
\machine\system\currentcontrolset\services\lanmanserver\parameters\nullsessionshares