This happens when either you (or some software that you installed) has altered the source's of the repository.
From a clean install of backtrack 5:
Using other sources other than the official repository, isn't recommended.Code:root@bt:~# wc -l /etc/apt/sources.list 4 /etc/apt/sources.list root@bt:~# cat /etc/apt/sources.list deb http://all.repository.backtrack-linux.org revolution main microverse non-free testing deb http://32.repository.backtrack-linux.org revolution main microverse non-free testing #deb http://source.repository.backtrack-linux.org revolution main microverse non-free testing deb http://updates.repository.backtrack-linux.org revolution main microverse non-free testing root@bt:~# cat /etc/apt/sources.list.bt deb http://all.repository.backtrack-linux.org revolution main microverse non-free testing deb http://32.repository.backtrack-linux.org revolution main microverse non-free testing deb http://source.repository.backtrack-linux.org revolution main microverse non-free testing root@bt:~# root@bt:~# ls -l /etc/apt/sources.list.d/ total 0 root@bt:~#
http://www.backtrack-linux.org/wiki/...ck_install_.3F


