Strange Network Problem

I've encountered a rather strange networking problem.

I have two PCs - both running Win2K - both cat5 cabled to a Linksys router - router connected to an AT&T DSL modem.

PC1 - stopped connecting to the internet. Cable and router port change did nothing. This PC was using an internal NIC so I disabled the internal NIC and added a PCI NIC card. Still no internet connection however I can do a file transfer between the PC's - which to me - says that the NIC is working, the cables are ok, and the router ports are working. What am I missing?

Larry

 

And, PC2 can connect to the Internet?

 

Forgot to add that - Yes - PC2 connects to the internet just fine. So my router to DSL modem to the net is working. PC2 can also use any port on the router to connect - so all router ports are working.

This is what has me stumped - I can't see any reason that PC1 is not connecting to the net. The only difference is that I have the NetBEUI protocol for PC to PC and TCP/IP for the internet protocol. I can't see how one protocol could work and the other one couldn't.

I've also un-installed the protocols re-booted and re-installed them - still no joy.

Larry