Hi, I have an iMac 24" 3.06Ghz, about six months old. I have started experiencing random but frequent complete system freezes. This is what typically happens over a period of 5 minutes: 1. I get the odd app crash (often Thunderbird, but possibly only because that is always running; sometimes mail.app crashes, something Open Office etc. No pattern to it). 2. The fans start thrashing although iStat doesn't record a higher temperature than normal. That said, the top bar hangs early on in this process so I guess the temp could be spiking. The box does not feel overly hot though (for an iMac). Normal temp about 39 degrees C. 3. All app windows freeze, and I get the beach ball. Mouse still works 4. dock freezes. Mouse still works. 5. keyboard freezes. Only mouse working now. 6. have to power off I also have a very annoying ghosting problem on the screen that has only just started happening. I am a relatively recent switcher to Mac, and have a lot of experience administering / developing on Windows XP. I'm happy to trawl through the logs, so could anyone give me any suggestions about what to look for, what could be wrong etc. Thanks D.