Not sure, but mine does this too. I like it in that I don’t have to navigate all the way to the end of the tabs to see the new one. (I have like 6 different windows open, each with like 50 tabs open….) Wait – if I go Ctrl+t, it opens a new tab at the end of everything, whereas if I right click on a link on a page, it opens it to the right of the current tab. Is that what yours does? My Firefox is v3.6.