No preview/hang?

I've tried to to a preview of the rule-matches recently, but the little gear-button greys out like it's doing something, but the panel becomes unresponsive. I've waited for it, but either it's hung or it takes more than 5 minutes to generate a rule preview.

Snow leopard, all updates, most recent version of Hazel. MB 1.83, 2Gb RAM. The folder it's running on has 50-100 items in it, few folders, and it doesn't go into folders.

Suggestions?

Edit: ok, I guess it just takes a loong time... and then doesn't match anything. Clearly I have some tweaking to do.

Next time it hangs like that, launch Activity Monitor, select System Preferences and do View->Sample Process. I don't know what could be causing it but hopefully that will give some sort of clue.