I have a iMac G5 20" and I've been experiencing problems ever since I got it and wanted to know if anyone else has had the same problem. Basically what happens is when I'm using an application (usually a web browswer, and it happens on all three Safari, Camino and Firefox) sometimes the multicolored spinning wheel will appear and that app will lock up. Furthermore I will hear clicking noises coming from the hard drive. As soon as I hear that first click I know the will machine lock up. I've tried to force quit the application but that doesn't work. I have to physically power down the machine to reboot it by holding down the power button on the back. It used to happen only once a week or so, but now it will happen every day, usually after an hour of using the iMac. Is this the iMac overheating, or is the hard drive faulty? I called Apple Support and they told me to do the permissions fix and reinstall the O/S. I did that but it didn't fix the problem. Has anyone else had this problem or suggestions on how to fix it? I'm basically at the point where I think my I need to replace my iMac. Oh, one last thing. This may be irrelavent, but the iMac has one Samsung 512 MB chip that came from Apple, and one 512 MB Samsung RAM I bought seperatly, but the RAM is matched 128bit. Thanks.