You have a classic temp. sensor issue, common with all sanyo projectors. Very easy to repair. Take the top cover off, check the little black pot like thing mounted nexto/on the lamp housing, It has a small white head... Thats the temp sensor. When the unit gets hot, the sensor opens the power circut, so that no power can come through. All you have to do is push the little white head back down, so that it closes the circut, and subsequintly restores power.
Here is the service manual free, It will give you alot more detail.http://yama.co.za/forum/index.php?topic=146.0