Problem: After running yum, Apache doesn't start.
This is the error from service_watcher.log:
Starting httpd: execvp: No such file or directory
Furthermore, apache is missing. If you don't have this, then it wont' run:
But yum install and yum upgrade didn't work. The solution is to do a force install on the rpm
# rpm -i --force /var/cache/yum/updates-released/packages/httpd-2.0
Saw this on Fedora Core 3