Jumping cursor

I recenty went from Windows XP to Window 7.  I also now have Micrsoft 2010 Home.  When I type on any of the suite programs, or anyother program I have to type on the cursor jumps all over the place.  Sometimes it even high lights words all the way up to the entire document I have been working on and then the next key I punch deletes everything.  It seems to be getting worse, that is it happens more often.  I called the help line and the tech was clueless.  HELP.