Fell performance on the graphics card

It all started with the fact that I had on my GeForce GTX 750ti was not enough performance (particularly in the new Mirrors Edge), I decided to try her strict drive through Afterburner. When running Mirros-edje plus in addition I launched a Benchmark from MSI, then got some errors in the utility appears, type SE not found. I fear all of the sliders back into place, turned off everything and rebooted the computer. What was my surprise when the Benchmark gave me only 4 FPS! I decided to go to CS:GO, where before it was consistently 90-120 fps, and now there on the strength of 25-35 fps. Reinstalled the driver - did not help. What to do?