Dear Macrumors Members I am a Mac user for years and I have some experience with troubleshooting and fixing/reinstalling Mac systems unfortunately I feel rather hopeless at the moment since I wasted hours and hours on trying to fix my 4months old iMac (the 27" edition). Ok so first of all, the problems appeared after some Apple updates, (it was a few months since my last update), I installed the updates and restarted my system and suddenly finder was broken, it just freezes all the time and I can't seem to open it and browse through my files and when I force quit it just crashes again. The only thing I can is use spotlight to browse for something (note that applications like iTunes and Photoshop work perfectly). Feeling desperate in this situation I tried to reinstall my Mac, so I inserted my Mac Install discs and pressed the ALT key while booting. The disc appeared but when I press enter my iMac just freezes and doesn't do anything. I tried a PRAM reset at this moment but that didn't do it either. I even tried different versions of Mac installs but with the same result. In the end I even tried to run my Discwarrior boot disc but it also crashes. So I can't seem to boot anything except my messed up Snow Leopard install. Note that I also tried booting from an external hard drive but with the same result. At last I tried booting in single user mode and I used the "fsck -y" commando but that gave me some Disc Errors. Ok lets get things clear, I want to format my Macintosh HD and peform a clean install, what should I do ?