laptop problems.

i have a toshiba p205d 7439 it has a amd athlon 64 x2 2 gigs ram running vista ultimate
the last couple of days i have had a problem with it. after it booted up and i try to run a couple of programs, it like stalls out for a minute or so. i try to click out of firefox or what ever and it does nothing. then all of a sudden it will close out of the programs i was tryin g to close out of all at once. like it went to sleep or something. the mouse (touchpad) will move around where ever i want it to but it will not click on anything. i can bring up the windows start menu by pressing the windows button on the keyboard but nothing else.

here is what i have done.
i have formated and reinstalled windows vista. took out and reinserted ram.
i am not sure how to go about diagnosing this. i am assuming this could be a hard drive, processor, or ram or even a mother board?
is there any way to diagnose this?