Major issues with Mbp and Apple Cinema Disp.

When I unhook my mbp from the 22" cinema display, the display on the LCD and performance starts to degrade to the point where I have to do a hard shut-down. I cannot do a safe boot. The only remedy is to reinstall Mountain Lion. I am unhooked from the ACD now using the LCD and everything is fine. But I know when I hook back up, then unhook the same thing will happen. I have experienced it multiple times.

Any ideas?