I have similar problems, it seems later versions of softice do not work with usb mouse, even if you checked usb mouse etc in troubleshooting configurations etc.

I eventually spent 10 bucks to buy a ps/2 mouse because any solution to a problem is a solution even though it's not ideal.

In my case, I can give some more information, softice seems to load ok, but ctl+d cannot bring out the softice console. And after softice is loaded, mouse no longer works. I tried to replace the defalt mouse driver etc, but none of the solutions worked. A ps/2 mouse solved all these problems instantly.

I can imagine a way to debug this problem is to use livekd+kd to figure out why the mouse ptr is lost and why ctl+d doesn't bring out the sice console.

While switching from usb mouse to ps/2 mouse, i had some
trouble with the registry, somehow the logictech mouse driver on the cd corrupted the registry relating to the mouse driver. I had to go to logitech website to download their latest utilities, fortunately it fixed the problem.

Hope this information helps.