My IMac doesn't boot.

Hi everybody, I've got a serious problem with my IMac 21,5" / 3,06 GHz , 4 GB RAM, 500GB (OS X 10.6.2)

(Excuse for my english, I know it's not very good)

I never had any problem with it (I have the IMac since 2009) and yesterday, I made a reboot and it got stuck at the starting grey background with the apple in the middle and the charging icon. I waited for over 20 minutes and it does nothing, and I've already tried the safe boot, restarting PRAM and all kind of hot keys that were supposed to solve my problem but actually, they did not. I remember I ran "Mackeeper 1.6.2" before rebooting it and it seemed to be okay, but I think it may have deleted some files or changed my configuration.
With the "Safe boot" it gets stuck in that lines:

"AirPort: RSN handshake complete on en1
DSMOS has arrived
"

Thank you for your help.

Mackeeper strikes agin I feel. It's an awful piece of software.
I would suggest that you are going to have to make a clean install of your OS I'm afraid, and do not install that junk again.