haunted mouse

[Eve]

We are currently having a prob with the mouse on the
computer with XP installed on it.It started last night.We
have just a basic PS2 mouse on this computer and it has
worked fine up until yesterday..now it acts like it is
haunted..it will move around the screen as if someone is
moving the mouse all around and it will come to rest on
the right side...but off the screen.We unplugged the mouse
and restarted the computer to still see the pointer on the
screen..it doesn't move but it shouldn't be there because
there is no mouse plugged in.I hope that this doesn't
confuse anyone...lol..also should note that we are having
hard drive issues if that helps. any advice would be much
appreciated..thank you in advance.