NIC adapter issues

Dell PE 6600 server, running Win 2003 Ent Ed R2, SP2//Embedded Broadcom Gig Nic.

I first encountered a "pci.sys missing or corrupt" error while booting. After swapping out the memory modules with known good ones the error continued.

I tried using the Recovery Man to replace the pci.sys file, but it could not read the c:\drive to that extent, so I did a Repair of the o/s.

Once the repair was done, I could ping the server from other servers on the network. Once I logged into the server the first time, I could no longer ping the server. I tried replacing the NIC drivers, still a no go. I can ping the NIC from the server itself. I don't think this is H/W related because i got a solid ping before logging in.

What other things should I be looking at?