Try double click on it. Or click and keep pressed, it should give a drop down list of previous pages. Or right click on it, for the drop down list of previous. Play with it, explore. It doesn't illuminate like IE (Internet Explorer)'s Back arrow.

Sorry, when I say "illuminate," I simply mean that when there is a previous page, the button darkens and has a faint drop shadow. This does not appear. Also, when the problem occurs, there is no drop list and double-clicking does not work. Thanks for the response though!

Also if you clicked on a link, it probably went to a new tab, if that's the case, it's first up in that tab, there would not be a go back action. You would have to go to the previous tab/ main tab of travel.

I was originally going to report the problem with PDFs, but then I realized that that was indeed the case. It was opening a new tab for them, but not for images.

Adobe PDF ( Portable Document File) That has nothing to do with anything.... but uhh go ahead, report your problem with them.

You were saying that Firefox might have been opening new tabs, and I thought I had a similar problem with the back button after opening a PDF but then I realized that Firefox was opening a new tab for it. I already knew that.

Some links require a new tab or even a new window. A tab is a sub window in a window. Adobe Reader pdf. has nothing to do with your request.

Nevermind, you aren't understanding what I was saying.