Early 2011 15" MacBook Pro rebooting by itself while surfing net

Hey guys,

So my Macbook has been rebooting randomly by itself quite a lot recently. It would mostly do this while watching a video on YouTube using Chrome, but sometimes just when surfing. It got to a point where it turned itself off at one point, and was unable to find the hard drive. I took it to Apple, and they found it to be a software corruption, and wiped my drive and reinstalled the OS. I stupidly copied stuff over from Time Machine, copying the corruption too apparently, as the problem persists.

At first I thought it was a problem with Chrome's in-built Flash and my installed version of Flash clashing, so I switched to Safari. Now what happens is I frequently get a message saying 'Safari Web Content crashed unexpectedly' (or words to that effect).

Here's the spec of my machine:

Any help would be appreciated. I can probably post crash logs etc, as I've been clicking 'Send To Apple' each time it's crashed.

Thanks in advance.

Joe