Hot and Crashing

Hello all,

I have a XPS 1645 laptop that had for quite some time now.  Not too long ago, I've notice that the laptop has been getting kind of hot lately.  My real concern was that the system was starting of freeze-up on me.  I've ran dell diag (f12) and I've cleaned the fan ports.  It seems to improve a little, but lately, when I leave it running and I return, I have to reboot cause it freeze-up when I'm away.

I ran Dell Online Diag, and I choose some of the stress test for HD, CPU, and GPU; unfortunately, the system never got a chance to complete the test. Almost immediately it crashed.  Catch22:  I can't find out whats wrong if I can't run program.

Thanks for your help.