nothing of what I could try works.

I suppose either there is a configuration mismatching between Matacity
and Compiz
or my Xorg.conf has a bad instruction. I know its a very senitive file.
You can mistake
in "menu.lst" (Grub config) without very important consequence, instead
some error
in Xorg.conf may induce a screen stuck.
I go on seeking, may be replacing that file by olders.