Samsung HLR5667w screen going black, powering off

[TNGSolutions]

I am having a problem with my HLR5667W. First I will give a background on what I have done so far. Initially I was getting the dreaded green checkerboard pattern on the analog channels, and the picture freezing on the digital channels that has been so prevalent in these sets, and after researching I determined that it was a bad digital board. Before I had a chance to replace the board the lamp went, completely blew. So I ordered a replacement lamp, but it's not a Phillips brand and I'm not sure off the top of my head who makes it. Anyway, after replacing the lamp the picture looked great and even lost the problem of the picture freezing for a while. Then it started again but not as frequent so I lived with it until it shut itself off one day. When I would turn it back on it would start up and the picture would come in nice and bright for about 15-30 seconds and then go black. I would have audio for another 10 seconds or so until it would completely shut down with all three lights blinking on the front. So I broke down and ordered a new digital board and replaced the old one. Fired up the TV, flipped the horizontal so the picture wasn't backwards and my picture came in nice and clear - for about 30 seconds when it did the same thing again. So I am at a loss as to what the problem might be now and I don't necessarily want to keep replacing parts that aren't going to fix the issue. Anyone have some suggestions on what I could try or what the problem might be? Thanks!

Sean