I think you are on to something. Unfortunately, I do not have that module installed. Perhaps someone else here has some experience to share with you.

As for Yahoo, I think you are fine. I have blocked them a few times before due to being on a host that limited CPU usage. The bots were running wild with my Amazon script. Finally, I added a crawl delay to my robots.txt and that was better. My point is that they kept coming back anyway and seems no harm was done so one time for you should not present a problem.

Good luck getting the mystery solved!

C