Brief summary of problem: Computer hangs when doing more intense stuff in applications such as iDVD, iPhoto, and Aperture. When it freezes, the only thing that really works is the mouse. Even when I rollover the dock, the name of the applications don't show up. In-depth examples: iDVD: I first noticed the problem with iDVD. I made a slideshow and was ready to burn a DVD. It would go through the common stages of rendering the music, slides, transitions, etc., then at a random point the computer would just lock up, and all I could hear is a tiny whine coming from the tower. Sometimes before it would freeze, I would notice that the image in the little preview window would look all "pixelated" or "scrambled". And the one time when it actually got to burn a DVD the image showed the same scrambled look. iPhoto: Sometimes when I open an image and do some adjustments, the computer would get into the same freeze. Plus sometimes it will give that same pixaleted or scrambled look to the image when doing some adjustments. It would go back to normal when I reset the settings. It would also do it when I would zoom into the photo as well. Aperture: (just installed yesterday) When I used the Loupe tool and was going over some sample images, I could tell it was working hard to process the information, then it freezed up on me again, like it did for iPhoto an iDVD. I first noticed this problem back in June when I was trying to make a slideshow DVD. That was with iLife '05. I installed iLife '06, samething. I took the computer to the Apple Store 'Genius'. They ran some test on it and couldn't really find the problem. He had a theory that perhaps one the processors wasn't working and when the computer needed the 2nd processor it would freeze up....not sure if that's the problem. I know this worked fine a bit over a year ago when I did the samething, but that was with iLife '04 and Panther, and I think a different video card; stock Nvidia 5200, I upgraded to an ATI Radeon 9800 Pro Mac Special Edition. Lastly one thing to note is that I had it to where it would ask for a password after coming from screensaver and when I clicked on switch user and it did that cube rotation thing, the image had the same scrambled look as it rotated. Small detail, but seems similar. Here are the specs of my machine: Power Mac G5 dual 2Ghz 1.5GB RAM ATI Radeon 9800 Pro Mac Special Edition (256MB) OS X 10.4.7 At least 60GB left on main start up hard drive Any ideas?