WinXP loses USB 2.0 drivers

Occasionally Windows will "lose" my USB 2.0 drivers and revert back to USB 1.1. A reboot always solves the issue. Any advice?

Gigabyte motherboard with nVidia nForce SLI chipset, WinXp sp2

I have seen mobos that would throw there USB drivers fairly regularly. in each case it was a warning sign that the usb host controller was defective and eventually lead to outright failure.