A buddies of mines laptop is really laggy, and is having issues. Stuff isn't responding or anything. He used to be able to play league of legends at aprox 100 FPS but now it goes from 100 down to 1-20 every few seconds. He has system restored and done a few other things, virus scans etc.. but with no luck, this has never happened, it just started a few days ago.
Intel(R) Core(TM) i5 CPU M 460 @ 2.53GHz
ATI Mobility Radeon HD 5650
Test the RAM modules with Memtest86+ : http://www.memtest.org/
Again, make the CD from the Memtest ISO CD-image file using IMGBurn.
Boot the laptop from the CD and Memtest will run automatically.
Test each RAM module on it's own for 3 passes so that if ram errors are reported you'll know which module it's relating to.
That will mean physically removing all RAM modules except one, testing it, then replacing that module with another one until they've all been tested.