User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.0; en-US; rv:1.9) Gecko/2008052906 Firefox/3.0 Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 6.0; en-US; rv:1.9) Gecko/2008052906 Firefox/3.0 At first I figured this was a PEBCAK and I was accidentally grabbing onto the "Back" item at the top of the menu so fast the menu would disappear right away, or maybe that there was a "feature" that double-clicking History jumps me back, and that my mouse was accidentally interpreting my click as a double sometimes. But then I started being extra careful to click it without moving the pointer, and it still happened occasionally. And intentionally double-clicking on it did nothing. So I have to assume it's just a really odd bug. Reproducible: Sometimes Steps to Reproduce: Click "History," especially for the first time on a page. Actual Results: Sometimes it opens the History menu, but other times it starts loading the previous page. Expected Results: It should always just open the History menu.
This seems basically a duplicate of bug 449879. Does it also happen in safe-mode? An extension like History Submenus could trigger this.