You can either turn off the debugger by setting the debugger.enabled switch in the debugger section of php.ini.
--OR--
If the Zend Optimizer still flakes with the debugger turned off, you might have to recompile php and reinstall over the previous install. This is the preferred method, to me anyway.
just make it without the --enable-debugger switch, make install that, then restart apache and you should be set.
Make a script with a single command in it:
phpinfo();
and execute that to see if the debugger is in fact off, and Zend on.