Problem with Nvidia geforce 9800 GT driver, while playing games

3 days ago i started having a black screen problem while playing games that normally would run on my PC ( for example League of Legends and Skyrim , the latter on low details ).

The problem is as follows : In League of Legends which i've been running on High details for 6 months now i started getting a black screen for about 2-4 seconds , afterwhich the game resumed. At least this is what happened for a while, but it started increasing in frequency and i had numerous Crashes (bugsplat errors) with a message saying that my video drivers have stopped working. This culminated with me also getting a Green Screen during the game that resulted in me restarting my pc ( basically the screen went green and i couldn't do anything else except manually restart)

The drivers are up to date so i have nothing to upgrade. I checked my video card thinking it might overheat and it runs at ~60C.

I cleaned the dust off my PC , reinstalled Windows and increased video card fan speed a bit.

Now i have almost the same problem, i still get the Black screen error that lasts 2-4 seconds and occasionally i get the Green Screen aswell forcing me to restart.

I decreased my League of Legends graphic details from High to Very Low, decreased FPS rates from 60 to 30 and now it runs without problems, but here's the catch: everything that worked smoothly before such as Skyrim and other high demanding games ( from a video card PoV) are now unplayable, i can only run older games like for example Warcraft 3 and LoL on Very Low details without getting Black screen / Green Screen problems.

I think that my video card is broken, but the thing is i can still watch HD movies / videos on youtube without any kind of problems. I only get errors in games.

Spec:
Procesor: Intel Pentium Dual-Core E5200 , 2,5 GHz
Ram: 2 GB
Video Card: Nvidia Geforce 9800 GT
OS: Windows7 Starter , 32 bit