flash fire from self-cleaning oven We have a self-cleaning oven (GE). We put in some stewing beef in a roaster into the oven at 300F for 45 minutes. After about 20 minutes there was smoke coming from the rear vent. When I noticed it I opened the oven door to see what was going on and had an extreme flash come from the oven, which burned my eyebrows and the hair on top of my forehead.

There were no spills in the oven (e.g. grease) of any kind. The side of the range was hot as if the self clean feature was on.

The first sign of something wrong was a week ago we were baking a frozen pizza. After about 20 minutes @400F (called for 23 minutes), smoke was coming from the vent and I just turned it off and left it as I didnt want to fill the house with smoke.  When I took out the pizza, the bottom was like thick rubber soles of boots and the top was scorched. Not a normal baking cycle.

Three weeks before this we baked a normal pizza. No spills on the bottom of the oven as the pizza was on a cookie sheet.

Can anyone tell what happened in the oven?
I don't think it really matters exactly what happened. Unless you've left out something important, it's not working right, and you need to get it repaired. The best case is that it keeps burning your food, and the worst case is that you set your place on fire.

If you want to confirm that it's doing something wrong, you could put a thermometer in it and turn it on (no food) and confirm that it's getting way too hot. (Edit: but please be careful, as Aaronut said. If there's any sign things are going wrong, turn it off, and leave the door closed.)