Lethargic Man (anag.)

I went to a shiur on the very subject (of why 9th Av is the chosen date) quite recently. Actually, now I think about it, it may have actually been on 9th Av. I can't remember any of the substance of it, and now I stop and think about it more, I may be getting it confused with another one I went to on the date of Shavuot. There's some link there. I'll have to figure out what!