Adept installatør, nogler emner er "dimmed"?

[Povl_Erik]

Jeg har set at nogle programmer som kan vælger er "dimmed", altså kan ikke markeres. Hvad kan dette skyldes. Betyder det at pakkerne ikke er tilgængelige, eller er min sources.list måske ikke komplet. Det drejer sig bl.a om alle Mozilla produkter incl. Firefox. Vedlagt min sources.list.
Håber nogen kan hjælpe lidt her

deb http://archive.ubuntu.com/ubuntu/ dapper main restricted
deb-src http://archive.ubuntu.com/ubuntu/ dapper main restricted

## Major bug fix updates produced after the final release of the
## distribution.
deb http://archive.ubuntu.com/ubuntu/ dapper-updates main restricted
deb-src http://archive.ubuntu.com/ubuntu/ dapper-updates main restricted

## Uncomment the following two lines to add software from the 'universe'
## repository.
## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
## team, and may not be under a free licence. Please satisfy yourself as to
## your rights to use the software. Also, please note that software in
## universe WILL NOT receive any review or updates from the Ubuntu security
## team.
deb http://archive.ubuntu.com/ubuntu/ dapper universe multiverse
deb-src http://archive.ubuntu.com/ubuntu/ dapper universe multiverse

## Uncomment the following two lines to add software from the 'backports'
## repository.
## N.B. software from this repository may not have been tested as
## extensively as that contained in the main release, although it includes
## newer versions of some applications which may provide useful features.
## Also, please note that software in backports WILL NOT receive any review
## or updates from the Ubuntu security team.
deb http://archive.ubuntu.com/ubuntu/ dapper-backports main restricted universe multiverse
deb-src http://archive.ubuntu.com/ubuntu/ dapper-backports main restricted universe multiverse

deb http://security.ubuntu.com/ubuntu dapper-security main restricted
deb-src http://security.ubuntu.com/ubuntu dapper-security main restricted
deb http://security.ubuntu.com/ubuntu dapper-security universe multiverse
deb-src http://security.ubuntu.com/ubuntu dapper-security universe multiverse

## dapper-commercial by canonical
## currently has realplay (realplayer 10) and opera (opera 9)
deb http://archive.canonical.com/ubuntu dapper-commercial main

## Bleeding edge wine repository for Dapper
## only uncomment it if you need it
## deb http://wine.budgetdedicated.com/apt dapper main
## deb-src http://wine.budgetdedicated.com/apt dapper main

## skype
## only uncomment it if you need it
## deb http://download.skype.com/linux/repos/debian/ stable non-free