Mitsubishi Rear Projection TV Blacks Out?

My Mitsubishi Rear Screen Projector Model VS-45502 has started to periodically black out. The picture, when working, is perfect, and the audio is unaffected. Turning the power off and letting it sit for a few minutes seems to help, but it is happening more frequently and staying black longer before the picture returns. What is the most likely problem and solution, and about how much would it cost to fix, given its age. Thanks.