Try cleaning the mouse. It could be dirt near contact buttons. You may have to open up the mouse for this, but a can of air will be a good way to blast away dirt and grime safely.
If this isn't the case, you very well could have a mouse going out, and it may need replacing. Good thing with this is, mice... are cheap, and often mice do run in the category of Field Replaceable Units with some IT repair-persons.
Last edited by ReaperX7; 09-14-2011 at 02:48 PM.