Few weeks ago I updated my mac os x from snow leopard to mountain lion. After the installation, some times the system run slow, and the last week the system run very slow. With this slow performance I think that the best is reinstall mountain lion from zero.

The first step has been make a backup with timemachine. Once the backup has been completed I browse internet for a manual that explain how to reinstall mountain lion from zero and I found the next manual on apple suport web.

https://discussions.apple.com/thread/4226282?start=0&tstart=0

I restart my macbook pro and follow the manual and after some problems with my itunes id password, the system start the installation from zero.

Now, Mountain Lion is installed and I have the hard task to reinstall and configure all the software. Ufff! :(