My computer was working fine up until 3 days ago, I only noticed the change when I went to watch something. It was working fine until 2 minutes into the movie and then my whole computer froze, not just the internet browser but everything, I left it for a while thinking it would return to normal but it didn't, it was still the same hours later. Not even the keys on my keyboard worked. I unplugged it as I couldn't shut it down, and when it restarted, it returned to normal. However, whenever I'd watch something the same thing would HAPPEN and I'd be forced to unplug it. Now though, whenever I do ANYTHING, such as uploading, downloading, INSTALLING, opening up applications (safe normal ones) it'll do the same thing and stop all together, like freeze. I even wiped everything off my computer, restarting the whole system or whatever it's called, and it seemed to be working fine but after a few minutes the same thing happened again. I've lost all my important files because of this. Also, whenever my computer reboots it won't start properly, the light on the side of the moniter keeps flicking orange and the same old ''no connection'' or whatever shows up beforehand. I've tried so many things but nothing seems to work.First of all, STOP UNPLUGGING THE SYSTEM TO SHUT IT DOWN. That is a shock to all electronic COMPONENTS. All you have to do is press and hold the power button. It will eventually shut down.

Second, please run diagnostics on both the ram and the hard drive:

To check the ram, download memtest (http://memtest.org/). Burn it to a cd using a dedicated .iso burning utility (http://www.petri.co.il/how_to_write_iso_files_to_cd.htm), make sure the cd drive is at the top of the boot order in bios, then boot to the newly created cd and run the utility.

To check the hd, download Seatools for DOS, burn it to a CD and run it: http://www.seagate.com/support/internal-hard-drives/consumer-electronics/ld25-series/seatools-dos-master/I know not to unplug it without shutting it down but I had no other choice but it, I had my finger on the shutdown button for ages but it still stayed in the same stance.I know this is going to seem like I am trying to fob you off, but if this really is URGENT then your fastest route to getting it fixed is to take it to your local computer repair shop. Though from reading your original post - assuming you only did a quick format and not a full format - If you want to possibly recover any of your important data, stop using the computer immediately. The more it is used, the less likely data recovery can be.

We could GO through the steps:
Overheating
PSU
Capacitors on the motherboard
HDD
etc

I am going to place my bet on the motherboard itself. Does the same condition occur if you simply leave it on the BIOS screen? Or in safe mode?