Since I installed Lion, the Spotlight database keeps reindexing (which is taking several hours). It does this at least every second day.

Are any other users experiencing this problem with Lion (i.e. is it just a 10.7.0 bug)?
If not, how can I diagnose what is causing it - I see no suspicious entries in Console? 

Just being able to reset the spotlight history and have it rebuild would be nice to know.