the inaccurate narration of events which ought not to have happened.

I do not get on lj as much as I used to. The past few days I have tried a couple of times. Now, it seems, this annoying box comes up on the screen where there are links or pictures. Apparently it is a snapshots box. This box has a little x to close it, but it does not work. It comes up in the middle of everything making my pages impossible to read. It just pops up, undefined, and if I click it, it takes me to the link the bottom of the box is pointing to.
This only seems to happen on LJ and only when using Firefox. It was only in using SAFARI that I could see what the boxes are and what they are for.
I turned off, then deleted LJ ADD-ONs, hoping it would help, but no.
Anyone else have this problem? Any ideas why my computer is having this issue? Oh yeah, it is a MAC.