Yeah, it was weird, and it was brand new batteries as of a week ago for another concert I shot. I think the reason it happened is because I left the strobe in the on position. It goes into sleep, but think it was still trickle-draining the batteries and when they ran out of juice and it was still drawing they probably got hot and burst or just burst for other reasons. Two of the four AA batteries in it were bubbled up on their ends and seemed to have leaked. Won't make that mistake again. I leave my batteries in my SB-600 all the time and have had that strobe for going on 6 or 7 years now. SB-600 is my backup strobe, and it's an awesome strobe to have. Think I'm going to get a 910 to replace my 900... but going to see if I can possibly fix the 900, but my guess it's dead for good. :( Good to know there are other Nikon shooters on Hubski!