Never run a mozilla browser using sudo, there is a bug that will indefinitely delete your bookmarks file (and possibly other files as well).
Hopefully this will be fixed before Firefox 1.0.
https://bugzilla.mozilla.org/show_bug.cgi?id=205053
https://bugzilla.mozilla.org/show_bug.cgi?id=251456
There’s also a new security patch for Firefox, download it here.