So, I recently upgraded to Ubuntu 9.04 and after by first boot was notified that the built-in search module is going to go ahead and index my files for faster searches. Fine.
But after a few seconds the Tracker got back at me and said something about my index being corrupt. It asked if I wanted to re-index everything again. Fine.
Apparently the index was still corrupt, so I gave it a bashing.
Fire up a terminal and enter the following commands to fix this minor annoyance:
sudo apt-get install tracker-utils
tracker-processes -r
The first command installs the utility you will need for the second command. Suffice to say, Ubuntu works fine now.