Windows 7 Freeze when network cable connected

[Guest Clay]

I have been running Windows 7 64 bit enterprise on my Dell Optiplex 755 for

 

two months now and it has been rock solid stable. However earlier this week

 

I came in the office and attempted log in and the system was frozen. I have

 

discovered that if I boot the system without the network card plugged in -

 

it works just fine. I can log in and work normally (without network

 

connectivity). But as soon as I plug the network card in the system

 

freezes. I have installed two additional network cards (one intel and one

 

realtek) but had the same results. As soon as I plug the network cable in

 

either card the system freezes. I did not find anything in the event logs

 

that gave me any clues as to why this was happening. I can log into safe

 

mode with networking and the system does not freeze. As consistent as this

 

problem is I thought this might be a known issue but I have not found

 

anything online dealing with my specific issue. Nothing new installed

 

lately that I can find that would have caused this. Not much running on

 

this machine, Office 2007 and VMware workstation 7 - maybe a couple of other

 

smaller footprint items. It is a domain joined systems connected to a

 

Active Directory 2003 edition. Any help is much appreciated.