We've had some issues where someone broke Crowd (they changed the LDAP credentials it was using).

One nasty side effect of this is that fisheye stopped sending notifications out. The real nuisance though is that all watchers appeared to be removed and needed adding back in manually.

I've afraid I've not got the full logs anymore but I can tell you this much:

(watcher error)
2010-04-14 00:00:00,097 ERROR [FE-WatchChecker] fisheye.app com.cenqua.fisheye.web.WatchManager$WatchChecker-checkWatchesForRep - Could not create trusted user login for user [mikeh]. Notification skipped for this user.