Whirlpool mirowave heats but fan/light dont work?

The fan and light on my Whirlpool MH6110XBB3 have stopped working all of a suddeen. Interestingly th elight works when I open the door but not when the unit is operating.

IT IS ACTUALLY HEATING FOOD OK, but after I run into for a minute or two in this mode it shuts down completely, which I'm guessing is some sort of safety mechanism to prevent overheating.

The Unit does make a humming noise but it is a lot less than usual, and thats why I feel it is the fan that is not running. I dont feel any air coming out the grille either.

Is there a fuse in there somewhere that needs checking? What do you think the problem is?