I removed the nVidia nForce LAN driver (completely uninstalled it) and am now using the Marvell Yukon 88E8001/8003/8010 onboard lan connector but I still get the same result...
Specs:
XP Pro SP2
ASUS Motherbard
AMD Athlon 64X2 3800+
2 gb RAM
Nvidia GeForce 7800 GT video card (3D Fuzion)