Previously, I had to play 60 fps.

Now, I had to play with 45 fps.

CPU: C2D E8400
RAM: 4GB DDR2
GPU: HD5770 Hawk.

Why?

When was "Previously"?

If the game used to run at 60fps then maybe anti-virus or some other background task was preventing that being reached again. We'll need more information before any better advice can be given.

1 week ago..then format:C .

Sorry, my english not so good.

If the game is running slower after a format try making sure your graphics drivers are up to date. It also helps to check nothing else is running in the background :)

GPU drivers are updated. Nothing run on background..only MSN and neccesary things.

Hmm... anyone else have any ideas?

Running 10.8 drivers? Try the 10.7.