I have 5 ThinkCentre M50 pcs all with the same issue. After a reload with XP and installing drivers from the website when a USB device of any type is plugged in the system crashes completely and reboots. If the device is left in the system shows the illegal shutdown message and then reboots as soon as XP starts and so continues to loop the reboot. If the device is unplugged then the next boot will work.
Looking in the event log I see minidumps reported for each crash and on startup it want's to send reports to Microsoft.
The USB drivers are a part of the Intel inf updater, I redownloaded the file and on expansion it complained that the expansion folder already existed so I am happy I have the same one.
Re-running the updater was very quick and did not ask for a reboot. Symptoms were the same.
I then opened device manager and chose to Update Driver, Not to go online, Select where to get update from and pointed it to the XP folder in the IBMTools\drivers\q..... This went through the process of installing files after which the USB interfaces appear to work.