Disappearing driver

I have a Dell Inspiron 4000 notebook. It came with ME.
I uploaded to XP with a disk. Short time later I
purchased a 3Com ethernet card for DSL. Many problems
and 3Com said it was a bad card. The next card had same
problem. Finally purchased a NetGear Card 5411 and
changed MY ISP.
Same problem: WHEN I INSTALL THE CARD THE DRIVER APPEARS
ON THE DEVICE MANAGER. WHEN I END THE SESSION AND CLOSE
THE PROGRAM OR, IF AN ERROR OCCURS, OR THE CONNECTION
FAILS, THE DRIVER DISAPPEARS FROM THE DEVICE MANAGER. IF
I REBOOT IMMEDIATELY THE CARD DRIVER WILL NOT BE LOADED.
MOST OF THE TIME IF I SHUT IT DOWN AND WAIT A FEW HOURS
OR SOMETIMES 24 HOURS IT WILL REINSTALL.
HOWEVER, THE SAME PROCESS IS AGAIN REPEATED. LOAD, FAIL
DISAPPEAR! I HAVE DOWNLOADED XP DOWNLOADS THAT I THOUGHT
MIGHT HELP. NOTHING CHANGES. WHAT DO YOU THINK? THANKS