Recently I have been having an issue where at least once a month my Spotlight index gets corrupted, and I can no longer search the content of mail in Mail.app. I can fix the problem by taking my HD out of Spotlight, and then putting it back in, but it then takes about 4 hours to re-index the drive.
Why is my Spotlight index getting munged? Do other applications besides Finder mess about with it?
Is there a way to keep the index optimized or repair it, such as when I repair a MySQL table?