emacs 24 c++ auto-indentation broken

I'm running Emacs 24 on Ubuntu 10.04, coding c++ in the default c++ environment. Periodically after a while coding, my indentation engine seems to break -- pressing "tab" to indent places places any line at the beginning of the line. Selecting the entire buffer result in the entire buffer being un-indented. This problem effects all buffers, current or later opened. So far the only way I have found to repair it is the (highly inconvenient) step of restarting emacs. Is there another way to reboot my indentation engine? Attempting to load different indentation styles does not fix the problem.