0 Why is Debian 6 asking for Install CD when installing software?

Example :

Change the source: Please, insert the CD labeled as «Debian GNU/Linux 6.0.1a Squeeze - official i386 CD Binary-1 20110322-15:11» in «/media/cdrom/» and press Intro (Return)

Fix :

/etc/apt/sources.list is referencing the cd.

Uncomment line what links to CD as first source.
Use nano or vi.
I use nano.Command is (must run as root) :

nano /etc/apt/sources.list