iMac boot problem

My dearest iMac have gotten itself into trouble. I've read my way into it's called the "circle of death". It plays the chime and shows an apple logo, the famous circle and below that, a loading bar which loads and dissapears after a few seconds.
My mac then goes very hot and does nothing.

I've tried to look in the recent topics in the imac forum but i was unable to find anything.

I tried doing the http://support.apple.com/kb/ht1379 steps but didnt do anything either.

Anyone got any ideas what to do? i cant be the only one this have happened to.

Regards.

 

I tried that, but it just went into the same screen as i described earlier.

I also tried to boot from the install disc and do a disc control and permission control, which told me that permission control has been changed and it was unable to change it back. i could neither repair the disc and the only solution would be to reinstall osx. which i'm doing now.