Thunderbird keeps asking me to open showthread.php!

[pbXassassinX1524]

Hey guys, I just installed Firefox again (cause mozilla was just too gaudy and big it seemed for my liking) and I swear I had uninstalled the last installation I had. Now, I click on a link from a thread notification from [H] and it (thunderbird) asks me to open showthread.php (like its some kind of file), but this is after Firefox has already loaded half the page and all seems to work fine accept it just keeps bugging me! Should I just try and uninstall and reinstall Thunderbird and Firefox (both newest versions, old thunderbird did the same thing) or is there something else I should be looking at?