Well there is this common misconception that bethesda made dishonored. They didn't. Bethesda published dishonored and arkane studios developed it. Dishonored also uses a different game engine than Skyrim. So there could be a few things that are wrong.
I don't think this is a problem with dishonored because the boards are not filled with complaints like this (yet).
Since your ps3 is first generation that would mean it is the oldest version (right?). Some older generations of the ps3 might have problems with dishonored that have not popped up yet.
Your hard drive could be corrupt... But you would probably see this problem in other games too.
You said that this is the end of you and dishonored. WHY? You can always play it again. Its a wonderful game. Did you plan on playing it only once?
Also if you do decide to restart the game I have some recommendations. Uninstall and then reinstall Dishonored. Save alot, even more than ever before.
Also games are hard to make they can have hundreds of thousands of lines of code. Its a lot to manage.
But anyways thats my 5 cents. Anyone correct me if im wrong im just speculating.