Locks with owner '0'

Ok, so here's a new one on me. This evening, one of the folks who runs the client applications for one of our databases told me that everything stopped working because of a lock that was being held against one of our central tables. I investigated with an eye toward finding out who held the lock, and then seeing what they were trying to do. Turns out we had a lock that looked like this (with some of the white space between columns cut out): a70ef68 0 0 a9a6528 HDR+ f0000d 0 0 The third column, owner, showed as 0. Stranger still, the type of the lock was "HDR+" which looks like a header lock, but with no type. Has anyone seen a zero-owner lock before? Anyone know the significance? We're running v7.31.FD6, which is fairly current in the 7.x line. We ended up having to bounce the engine to get rid of the lock, as I had no known session to zap. Odd. --John Bejarano, Shutterfly.