My problem is the next :
today morning I put on my mac an upgrade of Lion 10.8.5, combo update for 10.8.5 ( http://support.apple.com/kb/dl1676 )
after the reboot, the computer have the next message "your computer restarted because of a problem. Press a key or wait a few second to continue starting up."
I have read all this post in apple support ( http://support.apple.com/fr-fr/TS4636 , sorry this is in french) and I tried all what they are saying, but there is nothing to do because I don't want to go on Yosemite, but if there is no other solution.....
so I make a back-up of all my stuff.
Now i was thinking about reformat my system disk by connecting my compu to other compu in slave mode ( pressing T when it's starting). and after this trying to instal with a CD Lion. do you think this a good idea ?