Blue Screens, freezes and random restarts on my xps 8300

Hey all.

Im currently freaking out over my computers behavior of late. I think it started a week ago. I have windows 7 64 bit, dell xps 8300, dual screen monitor set up and it has been absolutely fine since i got it in i believe around 2011.

One day my computer froze twice after reaching desktop. Then it restarted it self before the official windows loading screen came up and another time before i reached log in screen. After another freeze, i then got a blue screen on the next load after reaching log in screen or something. Holding down the power button i turned it off, then it turns it self back on and enters the power button amber light flash 'sleep'. I turn it off again and leave it for a minute.

My next try i get to enter safe mode and i do a system restore point <ADMIN NOTE: Substitute character  removed as per TOU> 2 days back. The computer is fine for the next couple of days, but after shutting down i saw that windows updates were being applied.

After some time of being normal it begun the same horrible behavior i wrote about before. System restored again and decided to turn off auto windows updates so they haven't been installed. But this hasn't done anything since my computer is now doing the behavior AGAIN. Yesterday i got the amber light flashing again and later a blue screen about 'Page_Fault_In_Nonpaged_area' but after leaving the computer for a while i came back and it was fine for the whole night. 

Today i just got a blue screen about 'system_service_exception'.  There seems to be no trouble whilst in safe mode. Couple days ago i was able to use 'My Dell Support Center' and do a hardware check up which resulted in no problems found. I uninstalled the latest free superantispyware i got recently but that didnt do anything. I havnt installed any new hard ware into the tower. The only updated i can think of that i installed before this started happening was the new NVIDIA drive.

This is killing me. Any ideas? All help will be much appreciated.

Rhys.