I've posted about this in a few other forums, but decided to post it here as well because of the large number of mac users that traffic macrumors. I replaced my old 24" iMac with a new 2.8 GHz 24" Aluminum iMac this past Monday. I had zero issues with my old machine...unfortunately I haven't been so lucky with this new one. I'll list my issues which will lead into the crashing problems in the thread title. The screen definitely appeared somewhat yellow to me, which calibrating fixed for the most part. It stills seems somewhat more yellow to me in certain areas, but I have a feeling it has to do with the angle that you're looking through the glass. If I position myself in the middle of the screen and look to the right side, it appears somewhat more yellow. If I position myself to the right side of the screen, it now looks fine, and now the left side of the screen is what appears yellow. I'm not sure how thick the glass over the screen is, but it is a reasonable explanation for what I'm seeing on my screen. I had a kernel panic when I inserted a data dvd into my external nec-3550a that I have hooked up via fw400. It was pretty odd, and part of me wanted to blame it on the prolific controller in the device, but I've never had a problem with it before. I immediately thought about the 2x2gb set of ram that I put in the machine once I received it. I restarted the machine and ran the simple and extended version of the Apple Hardware Test. Came back fine both times. I decided that it was probably some crazy accident, and left it alone. I installed Unreal Tournament 2004, and this is where the real problems begin. After applying all the updates to the game, I load it up, and the game freezed completely within 5 minutes of playing. Mouse and keyboard are not responsive to any commands. Again, my mind drifts to the ram, and I decide to test it again. I then purchsed the CLI version of memtest and ran 5 passes in single user mode...all came back OK. Lastly, I downloaded a hacked version of memtest86+ that will boot on Intel Macs, and ram numerous passes overnight...all came back OK. I ran UT2k4 again, and of course it does the same freezing/crashing within 5-10 minutes of play. I turned off the iMac, and put in another 2x2gb set of ram I have laying around (I scored a hot deal on 2x2gb pc2-5300 so-dimms a while ago so I bought a few sets) and gave UT2k4 another go. Same result...UT2k4 freezes/crashes. I turn off the computer again, and put in the factory 1gb that came with the iMac and decide to give it another go...UT2k4 crashes again. It's definitely not a ram issue, which means it's either the video card overheating, or it's some driver/software issue. All updates were applied to the iMac beforehand, including the iMac Software Update 1.0. Seeing as how old UT2k4 is, and how many different systems it runs on, I have a hard time believing that it's overheating the video card, unless there's a manufacturing issue where heatsinks aren't being applied correctly. At idle I get a GPU temp of somewhere between 52-57C. Part of me really wants to believe that this is a driver issue, mostly just so that I don't have to send away my mac and be without a computer for God knows how long. Here's a thread in the apple discussion forums that I've posted in, and that shows other people with the same problems: http://discussions.apple.com/thread.jspa?threadID=1084445&tstart=15 Here's another with people having problems with the computer freezing/crashing/shutting off in other games including WoW, UT2k4, and Sims 2: http://discussions.apple.com/thread.jspa?threadID=1081362&tstart=0 Apple, please fix this problem with your machines, whether it be hardware or software related. I'm pretty pissed off at the moment. When I first got this new iMac, I was pretty upset at the performance of the ATI 2600 compared to the 7600gt in my previous iMac, but now I don't really care about that, because framerates and performance mean nothing if I can't play the game for more than 5 minutes. Hopefully more of you out there with new iMacs can help reproduce these problems and we can make it more public which should help Apple get their ass in gear and fix the problems.