Sometimes I managed to keep the ACR window and LR in my installs, but I never managed to figure out how or why. And then, all of a sudden, ACR would disappear after installed OpenDoc or some other software ( I'm a Mac user ). And also, all options to re-enable access to ACR from within bridge simply disappeared. But, it also worked after installed Flash CS3, so I don't think this is a setting exclusive to LR.
Since I can't control how and when this happens, and when it happens, re-enable in any easy way, I learned to work on LR and PS, without bridge or ACR.