I have been having freezing issues w/ my late Nov 2007 20" iMac 2.4 Ghz lately. And, i would like to know what is causing it. And, perhaps find out if it is an isolated case or something like an epidemic. These issues would start out w/ apps, like, PSE 4, for example, unable to force quit. The PSE icon in the dock is still lit up, but I can't reopen or do anything with it. I have had this problem before but it has recently been more frequent. Last night, I had to shut down the computer 3 times within a few hours of each other. Not good. Since, these freezes have been occuring more regularly, I know exactly what the computer will do or won't do. For example, if I have an external firewire drive that is docked, I won't be able to eject it. So, the problem creates a kind of like chain reaction. While some apps are unresponsive, some apps remain responsive. So, I can use Safari to browse the internet, for example. But, I can't continue to use my computer normally b/c it is obviously not behaving as it should. I wanna restart it! Or, better yet, go into Activity Monitor and maybe force quit the unresponsive apps that way since hitting right click on the mouse or cntrl-alt-esc doesn't work either. Maybe, I can do it in Activity Monitor, I say to myself. But, inevitably, Activity Monitor will not start and this usually freezes the entire computer, in which case I have to shut it down by pressing the power button. I wanna throw the computer out the window or do a clean install and not upgrade to leopard. My iMac came w/ a separate Leopard CD that I had to install myself. It originally had Tiger in it. My reason to stick w/ Tiger is that my 5 yr old powerbook w/ OS X 10.4.11 never has these issues. I have already started backing up my files, in case, the iMac dies. I hope it gets better. I really don't want to have to shutdown the computer 3 times every night b/c of these freezing issues. If it continues, i will probably have no choice but to do a clean install as annoying as that is. Sorry for such a long post. But, I really wanted to make sure to be as detailed as possible in the hope that it might be diagnosed easier. Any input, solution will be much appreciated. Thanks in advance.