My iMac ran a software update last night, but the program kicked out before it completed. When I went to reboot this morning, I had the Mac icon on a grey screen, with a little line rolling around in a circle below it. It's been hung up there all day. I've read in other posts that I should do a clean install of the system software. Problem is, my hard drive is absolutely packed and the computer is telling me that I don't have enough space to do even a baisc installation without all the bells and whistles. Because the machine won't boot, I can't get into the drive to transfer or delete any files in order to create the necessary space for the installation. Any suggestions?