As Alexander Sack pointed out to me, this is probably due to this bug:
https://bugzilla.mozilla.org/show_bug.cgi?id=440840 -- Firefox3 does not remember application association https://bugs.launchpad.net/bugs/243704 You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs