My late-2008 MBP keeps restarting itself I posted this on the apple.com forums, but haven't gotten an answer

Hi,
I know this has been asked, and I've read a ton of posts here and other places, but still not sure I know what's going on. 
I have a 15 in late-2008 MBP. The battery had to be removed a year or so ago because it had swollen up to the point that its was affecting the trackpad, and as I mainly work at my desk, I've never replaced it, and so obviously, only use it when it's plugged in.

It's a 2.4 ghz intel core 2 duo
2GB 1067 Mhz DDR3
Graphics: NVIDIA GeForce 9400M 256MP
OSX 10.9.2 (13c64)
250GB HD (which is almost full and I'm currently working on cleaning off... mostly pictures)
2GB RAM (I thought it was more?)

So, if left idle, it will usually restart itself, or if I close the top it will almost always restart itself while closed. I never get an error message though.

It's sluggish, but I'm sure that's because of the full HD. Otherwise, it's still working good, but it is most annoying and quite concerning that it restarts about 15 times a day!

Please help!
You could try following investigating method using Terminal.

﻿What is shutting down the computer

syslog -k Sender kernel -k Message CSeq 'n Cause: -' | tail | awk '/:/{$4=""; print}' | pbcopy


The output is in the clipboard, so paste it in a text program like Notes or others. You can paste it in here for us to help you evaluate the result.