The first thing I would try if encountering a problem such as this
(besides turning the surrounding area a bit on the blue side, that is)
is reboot the computer into Safe Mode.  You can get into Safe Mode by
pressing the F8 key once the computer has started to reboot.  Look for a
flashing cursor on the top left hand side of your screen and press the
F8 key before the Window logo appears.

Once the system is fully booted up into safe mode, you might want to
check your mouse but may not be able to see or access the Start link due
to the low screen resolution.

You should be able to see the "My computer" icon...click on that and use
it's shut down feature.

Once the system is shut down, reboot it again as you normally would.

Try you mouse to see if the problem has cleared up.....if it hasn't then
you will have to go a little deeper to find out exactly what the problem is.