MacBook Pro :: 13" 2011: Lines On Screen?

I bought my Macbook Pro 13" in 2011 March when the line was refreshed. About 6 months later there were vertical lines running across the screen, and it hangs. Once I've rebooted by pressing the start button it all goes back to normal. I thought it was some random bug so I didn't check it out. A month later it happened again, and again and again, although it was so random that I couldn't pinpoint when it would happen. I brought it to Applecenter.They changed the logic board. I brought it back and reinstalled new applications – it happened again, this time with vertical lines and 3 beeping noises. (I've got videos and pictures to prove it -- even took videos showing the serial number because some of them were skeptical if it was the same laptop!) I brought it to Applecenter again. They reformatted the hard drive, and I took it back. The problem remanifested itself after a few days.I brought it back to Applecenter AGAIN. They did hardware testing, etc and couldn't find anything wrong with it. The engineers told the people at Apple to do a zero-out (because it might not be done right the first time) I took it back. They said it might be a software issue. So I was careful to have clean installs of everything.And then it happened again. And again. They did not want to replace my laptop and want to further troubleshoot although it's been 3 times at this point that I have returned back and forth to the Applecenter.Tech people told me to do a partition and watch out if it happens on the clean install. I think it's not a software issue at this point, but I am very frustrated. I can't just keep waiting for the clean install to mess up – I need to work and all my applications are on the other partition!  

Info:
MacBook Pro, Mac OS X (10.6)