ps3 is freezing

Have you already tried to reset your console: 

1. Turn off Playstation 3.

2. Hold The power button down; The system will turn on and turn off once again.

3. Once the System has been shutdown, re-press you finger until you hear 2 consecutive beeps

4. When you hear the 2 beeps take finger off power button.

5. You will be prompted to plug in your controller via usb and then hit the PS button

6. The Recovery menu will pop up.

7. Select Restore File System.

This will delete any corrupt files off of your system. It won't delete any game data. It might still worth a try to remove all DA:I game data (not your savegame files) from your system in order to re-install the game.

Cheers
Basti