Instead of that link, use this one in your sources. See if it fixes the problem.
http://downloads.sourceforge.net/project/ubuntuzilla/mozilla/apt/pool/main/f/firefox-mozilla-build/firefox-mozilla-build_10.0-0ubuntu1_i386.deb?r=&ts=1329168082&use_mirror=superb-sea2 --- Ubuntu Bug Squad volunteer triager http://wiki.ubuntu.com/BugSquad
Instead of that link, use this one in your sources. See if it fixes the problem.
http:// downloads. sourceforge. net/project/ ubuntuzilla/ mozilla/ apt/pool/ main/f/ firefox- mozilla- build/firefox- mozilla- build_10. 0-0ubuntu1_ i386.deb? r=&ts=132916808 2&use_mirror= superb- sea2 wiki.ubuntu. com/BugSquad
---
Ubuntu Bug Squad volunteer triager
http://