I'm sorry to hear that you're having this issue.
One troubleshooting tip I can offer is to reseat the lamp. Unplug the TV, open the back cover, unscrew the lamp from the housing, slide it out a few inches (removing the lamp isn't necessary), and then pushing it firmly back in. Screw it back into place, close the cover and then restart the TV.
In some cases, the lamp can be moved out of place due to movement of the TV - but some people who say that the TV hasn't been moved still were able to claim that this successfully fixed the problem.
If this doesn't fix the problem, I would recommend having the unit inspected by a qualified technician.
I have been having problems for a while with the TV turning itself off without any warning. It started about a year ago and now it is turning off every fifteen minutes or so. The green light goes off and the red light comes on. We can turn it back on but it becoming a real pain.
Thanks for any help you might be able to give.