Since the last couple updates, every computer I have Firefox installed on will not allow me to close an individual tab. I have to close the entire browser. This is very frustrating when you end up having many tabs open and you can't close any of them. I thought it was only happening on my 3 computers, however, when I installed Firefox on my mom's brand new laptop two days ago and was excited to show her the benefits of Firefox v. IE, I was very disappointed to find out her computer has the same problem.

FYI, this post shows my computer as having Windows XP. However, I'm also having the same issues on three computers with Windows 7.