I've set rendering in Beryl Manager to "copy" (beryl-manager -> Advanced Beryl Options -> Rendering path -> Copy).
Since that when I start Beryl Manager I get a graphic system crash.

My simple question is: How can I reset this setting to the default without having to start Beryl Manager?

In your home directory, check out .beryl-managerrc and the directory .beryl

OK, it's solved someway with running beryl-manager with the parameters "no-force-window-manager" and "no-force-decorator", some of them solved the problem.
So now I can use Beryl but I have another problem: window borders are white (when maximized). What should I do with this? I know this is a common problem, I've tried some solutions but none of them worked. My graphic card is ATI radeon mobility U1 (IGP 320m). If it's important I'm using the xorg and .drirc settings described here.

EDIT: also solved. I just had to put the .drirc file to /etc.