I am using an onboard intel video card (D945 chipset). Anyways, I want to install my ATI X300 64meg video card. But when I install the card and boot up, my Intel Pro1000GT network card quits working. I remove the ATI card, and the network card returns to normal.
The D945 doesn’t reach my native resolution of 1680x1050, so I am trying this X300.
Try, after installing the ATI, to turn off the computer and completely unpower it, that is, if its a laptop, pull out the battery and unplug the power cord, if a desktop unplug the power cord and switch off the feeder (should be a red switch on the back)
This way you completely discharge the chip, which might retain some wrong settings thus causing the network card to work improperly.
I had a problem of not connecting in a dual boot and that completely solved.
Worth a shot, its simple , quick and risk free