Cannot connect to http://localhost:631

["J. Zidar" <zee@email.si>]

I have a HP Deskjet 656C printer that I would like to set up using CUPS,
but when I try to connect to http://localhost:631 Mozilla complains about
not being able to connect to that server.Running the command cupsdconf as root 
gives the error:
Unable to retrieve configuration file from the CUPS server. 
You probably don't have the access permissions to perform this operation.

CUPS are installed (I can see cupsd running). The printer is connected
through a USB port. The modules were loaded without any complaints from
the kernel. I'm root while doing all the work.

Thanks for any advice.

Jernej