Let\'s say you have a bug that was found in functional testing of a fairly complex part of the software. It could stem from bad/unexpected data in the database, middle-tier cod
In my experience, it's probably best to go with gut feel (1) for 30 minutes or so.
If nothing comes out of that, talk to someone else about it.
It's quite amazing how talking to someone else (even if they're non technical), can help.