My iMac will chime, then hang on the grey apple screen with the spinning gear. After a few minutes, it shuts off. Tried resetting Pram and all... Did not work. I troubleshooted using another website, and found it to be an I/O Error. The issue is I need to reinstall the OS, however, when I boot the install CD it hangs the minute I click the mouse or keyboard. Not sure how to fix this, any insight is appreciated. Thanks.