Just joined this forum as this thread is of interest to me.
I also have a dell, an Optiplex GX260, win XP Pro SP2.
I also have the same problem, the network cards (one motherboard, one pci) have both disappeared from the device manager and right clicking, properties, on "Network Places" gives a blank screen.
I have completely reinstalled XP Pro, then added the updates inc SP2 again.
I have updated the bios.
I have updated the chipset drivers.
I have changed the clot of the PCI card.
I have checked the PCI card in another machine and works fine.
I have downloaded SPYbot and run - just incase.
I have downloaded and run AVG - just incase.
I have also tried all of this .... http://support.microsoft.com/default...b;en-us;825826
with no result.
Interestingly, the network cards still work!
Using IP config gives all the usual expected information from a working card, however doing "getmac" gives the answer that no adapters are present???
Anyone want to prove their worth and solve this...i've spent 4 man days trying to figure this out, searched lots of forums but have drawn a blank everytime............