Laptop won't shut down or log in

For several months now my laptop (dell studio 15 with 64x windows 7) has worked perfectly, however out of the blue, with no warning like an update or reboot, I was simply playing a low budget game, my computer started to consistently freeze as i clicked my mouse around the screen. naturally it eventually froze completely so I had to force a restart, after the restart it told me it hadn't shut down properly, as expected. i booted up normally to find that after trying to access any of the user profiles, i loaded into the user and would sit at the loading screen for a very long time, and eventually boot in to a frozen default background and start up bar, I could move the cursor however nothing could be clicked. The windows start bar would eventually dissappear as well.

back at the user selection screen i tried several times to do a proper restart and shut down, restarts were successful in restarting, however it would still say the computer did not shut down properly, and shut downs just did not happen, they would sit at the restart screen.

I booted into diagnostics to run a full system scan, and it stopped itself after 79% on a hardrive from what i can deduce where it failed a test (im not computer savvy when it comes to all the numbers it displayed).

On a side note.. my system restore disk that came with the computer is damaged, so I have no idea how I'm going to solve this..