It seems that either your xulrunner-1.9 is not matching your firefox-3.0 or that something is broken (missing or broken lib).
Please, show us: $ dpkg -l | grep -E ' (firefox-3.0|xulrunner-1.9|libnss3|libnspr4)'
It seems that either your xulrunner-1.9 is not matching your firefox-3.0 or that something is broken (missing or broken lib).
Please, show us: 3.0|xulrunner- 1.9|libnss3| libnspr4) '
$ dpkg -l | grep -E ' (firefox-