The oven usually works, but it is increasingly displaying the word "door" on the display and turning off, even if the door is closed and/or locked.

The only solution I have at this point is temporary, open the door and slam it shut, turn off the oven and then turn it on again. This usually works, though it may require serveral attempts.

Any idea why I'm experiencing this problem? I would state the model number but I'm not aware of what it is. I don't personally own it so I can find out the model number if necessary.