running tiger 10.4.11 on imac - after downloading the new version of skype (which i discovered would not run on my os), my machine came up with the need to restart message - which i did 5 times. then i tried the apple hardware test disc -which would not run and is still in the drive. as a last resort i went into command mode to try and fix permissions - but the machine is just hanging 12 hours later. i tried exit and reboot with no effect either. i need helppppppppp thanks.