Having the same problem here with Ubuntu Natty and Unity Enable,
My setup is the following PC with two graphics card,
ATI HD 6950
ATI HD 4670
Both graphics are properly working monitors are detected and configurable, but when Xinerama is enabled then unity is not booting and X crashes, the only way to login is restarting gdm from a terminal and setting as session ubuntu with no effects.
it seems that unity and compiz is not properly working in multiple monitors environment.
Having the same problem here with Ubuntu Natty and Unity Enable,
My setup is the following PC with two graphics card,
ATI HD 6950
ATI HD 4670
Both graphics are properly working monitors are detected and configurable, but when Xinerama is enabled then unity is not booting and X crashes, the only way to login is restarting gdm from a terminal and setting as session ubuntu with no effects.
it seems that unity and compiz is not properly working in multiple monitors environment.