This is using Optimize Press Theme, but that may not be related. Often, but oddly, not always, when doing an edit of a post, whenever I type the letter "B," (upper or lower) WordPress opens a buffer that has a copy of whatever is being typed and gets it ready to Tweet. Obviously, this is some sort of shortcut key that has somehow been enabled, but we can't find anywhere to disable it.
Tonight, it also happened while writing a comment to a posting on someone else's blog. I searched on a bunch of things here in the forum, but guess I couldn't come up with a unique enough string to narrow to something useful. Any suggestions?