I don't know if this will be of any help, but when I was trying to save money with my X10 I purchased a non-OEM housing/bulb. When I plugged it into the projector there would be white lines, the reds would smear, and there would be white shimmering. It was a horrible mess. I then took the bulb and put it into a OEM housing and suddenly everything was fine. I was thinking that perhaps the bulb might be the cause of your problem. Have you tried taking the bulb out and putting it back in? Unfortunately you can't do the exchange bulb thing so easily with the IN72 since the housing is pretty complicated. I have a IN72 I use quite a bit but haven't experienced the problem.
From the sound of it, though, it does seem your projector might be on its last legs. I work in IT and see LCD units (I know yours is a DLP) go out and I've seen the white line problem happen before. Have you tried resetting your projector back to default? Maybe one of the settings is causing a problem. I know that with my X10 if I set the BrilliantColor setting sometimes I get half a good picture and half yellowish. It's ugly. When I turn it off everything is fine. Make sure you unplug everything other than the power to do the test so you don't have any external factors involved. When/if it's determined that everything is good then start putting your component cables back in to the projector one by one.