Try changing them directly from the video card proprieties or panel. Maybe your own graphic card is blocking them.
Or, restart, and change them back manually from the regedit.
Change the x and y resolution manually to value data 300 (x) and 400 (y) or try 800x600 by typing 320 (x) and 258 (y). Does it keep those numbers?
Clean some of your services and startup stuff.