I new-tab a link and if I leave that page and look at another I can't go back to the original page.

So I'm surfing on something like wikipedia and I see a link (B) for something related to the current article (A) that seems interesting. Because I don't want to leave (A) just yet, I right-click, then new tab (B) and continue. Now if in (B) I decide to look at another link or a picture (C) on (B) I can't go back to (B) afterward. The back button just forgets that it ever existed. Sometimes I'm lucky and I still have (A) up or (C) has a link back to (B) but Firefox 3 didn't have this problem.