Computer Randomly Shuts Off

Hello,

I don't know if anyone can help me, but it would be great if I found a solution.

I have an HP-Pavilion 1465dx series laptop. I have had it for 4-5+ years. The laptop will randomly shut down when not plugged in. I used to think it was a battery issue so I switched out the batteries and still experienced the problem after a time. Then I thought it was an overheating issue but it happens even when its in a ventilated area. The computer will shut off and I cannot restart it without pulling the CMOS battery and rebooting. I replaced the CMOS battery and this is not the issue. I've replaced the charger, and updated the drivers etc. Nothing seems to work. If I leave the computer unplugged in a low power state for sometime it ends up shutting off randomly when I go to use it (even if the battery is reading with power still). I don't know if this is bad memory.. Bad motherboard or what... I have ran all the diagnostic test long and short, virus scans, etc and nothing has come up with an issue so I don't know what else to attempt..

I am currently running:

Windows 7.
HP Pavilion 1465dx
Service Pack 1
64 BIT OS
Intel Duo 2 Core T6500 @ 2.10GHz

Any suggestions? Thanks.