This problem has given me so much trouble I decided to start with a fresh install of XP SP2.
**The Problem**
I recently purchased a Netgear WG111T USB 2 Wifi Dongle and a MSI 1.5GB USB 2.0 mini Drive
until I started using these USB2.0 was not an issue on my Trigem Kloss Pentium 915 chipset SFF PC, I did have a USB1.1 wireless keyboard with built in mouse from the start but then its not a 2.0 device so I didnt have a problem.
When I connected both the MSI and Netgear USB 2.0 Devices I get the message from windows these devices can work faster, so I paid a visit to my bios and found USB turned off, and Turned it on, enabling all 8 ports at Highspeed (480Mps) there is also an option for 12Mps.
Now when I reboot windows everything works fine for like 5-10 mins and then total lock up.
If I restart windows the system gets just passed the XP splash screen then hangs.
if I restart XP and pull all USB 2.0 devices or disable USB2.0 in the bios everything is fine again.
So the problem is I just cant use USB2.0 Devices at USB 2.0 speeds without my system locking up eventually