Normally, when having odd USB problems a good place to start is to delete (uninstall) all of the USB controller and let Windows redetect (right click in the device manager window and select "Scan for hardware changes".

Peter

Are you using the USB ports on the front? Try one of the ports on the back. I have had issues with some devices using the front USB ports. (I don't know if they share a port or bus or whatever)

Yes, that is a problem. I just tried it on my 9100 with USB only keyboard and mouse.

When I deleted one of the controllers, my keyboard and mouse stopped working.

What I did is this:

I have WinVNC (free remote control program ... very useful) running on that machine, so I could finish deleting the devices from another machine. If you have this option, you can right click in Device Manager and "Scan for hardware changes" right away (without rebooting). The devices come back, including the mouse and keyboard.

I also have the power button programmed to power off the machine. That is useful when the keyboard/mouse have a problem. I can always shut the machine down in an order fashion (as long as no program needs input to shut down).

You can also move your mouse to last working USB port. When you delete that USB controller, you will need to press the power button to shut down the machine.

Having a PS/2 port does have it's advantages. I wish I ordered the $10 option for my machine.

Peter