single left click selects then deselects at time

for example say I am clicking a check box. 2 out of 3 clicks will select the box then deselect the box.

another example:
when i click back in internet explorer it will go back 2 times

another example:
when i click file it will open quickly with the options, then disappear........

HELP. what is going on?

are you sure your mouse button isnt sticking physically?
have you tried another mouse? a different port? drivers?

What mouse? I had a conflict with MX500 mouse and Vista's mouse driver. I had to reinstall the Logitech mouse software because something similar would happen. When I clicked a button, the release click seemed to count as a down click also essentially making it click twice.