check the heating element in main oven, it might have blowing, and thats what triping it, you need to get a look at it, turn the power off and take the back off to see it, you will know by looking that it has blowing , replace it, with the same shape/power one, its not that hard to do ,take a photo of the 3 wires going to the old element, and put them the same on the new one, but have All power off when working on it, be safe..
j, December 2011