My laptop unexpectantly shuts down instantly

Registration date
Tuesday September 11, 2012
Last seen
September 11, 2012
- Sep 11, 2012 at 09:47 AM
my laptop is a HP pavilion dv7 notebook pc, intel(R) Core(TM)2 duo CPU P7350 @ 2.00GHz

laptop is about 5 years old.

Awhile ago about last year there was a storm and the storm killed my battery it doesn't work anymore but i haven't bought a new one, i also accidently broke my original power source as well so i currently have a power source that isn't its recommended power source but it keeps my laptop running and I've had it for about 8 months now, so recently about 3 weeks ago, my laptop would turn off instantly after logging in with my power options on high performance, and now when i play in power saver league of legends after it loads all the champions in about 10 secs after it shuts down instantly I've even felt the computer and it barely gets any heat at all, yet when i play Warcraft 3 or world of Warcraft it doesn't shut down at all i can keep it running all day I've gone to the point where its really warm on my computer to see if heating was the problem, I've literally took my computer apart and cleaned my fan thoroughly and even though i have a power source that isn't for my laptop or a functioning battery I've never had this problem before I always keep 2 good sized external fans at each sides of my laptop to cool it down because i never let it heat up but i did once to see if it heating up was the problem it wasn't, does any one know what might be the problem?