USB Wireless Adapter kills computer

[#1]

I have come across a very unusual problem.
My daughter has a Speedtouch 121g USB wireless adapter and something has gone badly wrong.
With it installed the computer won't boot. It just crashes and restarts. This isn't an XP problem as it doesn't go through the BSOD phase. It's just as if the reset button on the case was pressed. Previously it worked without problems. Have tried on other USB slots. The other USB connected items work OK.
Uninstalled the software and rebooted and the computer starts fine but when the software is installed and the adapter inserted as requested it restarts the computer at the point where the software initiates the adapter.
I have posted a replacement unit to her but in the meantime does anyone have any idea what could be causing the problem other than  a faulty unit

[#2]

Hi Jim
The last time I had a similar problem it did turn out to be a faulty USB device shorting the power lines on the USB socket.
I've also had a collapsed USB socket on another PC which subsequently refused to boot fully.

[#3]

I have seen this with a netgear WiFi adaptor too.
Machine would not boot if it was connected, and if you plugged it in once it had booted it just reset the machine.
Chilly

[#4]

Thanks - will see if the replacement works otherwise a wireless PCI card will be ordered

[#5]

Reploacement failed as well and as both worked on my other PC's it must be a motherboard problem or a conflict with the wireles keyboard.
Either way I have now ordered a PCI wireless adaptor