Hi,
My PC at work has a mouse and keyboard problem: At XP login prompt the mouse works fine. When I touch a button on the keyboard (or Ctrl-Alt-Del if you wish) the mouse cursor is blocked.
I tried changing only mouse, only keyboard, changing both, but the problem insists. The only solution is to put a USB adapter for keyboard and mouse.
Any ideas???

Thanks for your time !

What do you mean by a USB adapter? Are you adapting from USB to PS/2? If so, why is that a problem?

I'm of the opinion that if PS/2 ports are available, they should be used. Save the USB ports for other external devices.

Other than that, check your BIOS for settings related to USB keyboard & mouse.

"And that's the fishing line, because Sharkboy said so!"

I use an adapter that connects my PS/2 keyboard and mouse to a USB port. This is the only way to use them.
I changed the BIOS to the default. Same situation.
The strange thing is that from a Live CD everything works fine, so it is not a harware failure...