MB Pro won't boot normally; gets KPanic screen all the time.

Yes, those!

My MB Pro started showing the dreaded "Shut off or restart your computer..." messages whenever I tried to fire it up.

The first time I got that message I was using the usual apps (i.e. Safari, Mail, iTunes, Transmission, etc...) nothing unusual. I left my Mac downloading some file and when I came back the screensaver was on so I pressed a key to start using my Mac again. After pressing the key the screensaver froze and the colors started looking choppy and distorted so I decided to restart the laptop. When it restarted it showed me the "Shut off or restart your computer..." screen so I restarted again... I did that 3 times in a row until it booted normally and that was it.

The next day I took my Mac to work and turned it on but the dreaded screen came on again; I restarted for 5 times in a row this time until it booted normally. Last Saturday I turned my laptop on and got the same #@^& screen again, I restarted but haven't been able to boot normally since.

I have to add that the same day I got the first kernel panic screen I ran a full test with TechTool Deluxe; it tested RAM, HD read and write and also did a surface check. No issues were found.

I did some further testing removing both 2 MB RAM sticks from my MB Pro and using some other sticks I had to test the RAM but still no normal boot so I don't think it's the RAM. I installed my wife's 120 GB HD that I took from her MBook and installed it on my MB Pro and STILL no normal boot.

I decided to install my 320 GB HD on her MBook to see if my HD was the culprit but guess what!? The HD boots normally on her MBook. In fact, I'm writing this topic using her MBook and my 320 GB HD!

Could it be determined from all my testing that the culprit is neither the RAM nor my HD?? I have yet to take my beloved MB Pro to any technician; I wanted to do some testing of my own first.

So, from what I've told you, do you have any suggestions on clues on what the problem might be?? All is left is the Logic board... I think!

Thanks in advance