I've recently bought a laptop ( a Packard Bell Easynote B3561) with Realtek
ALC 655 audio system and decided to install Debian on it as my desktop.
During the installation there did not occurred any major problems even
my USB mouse was miracally recognized. But after the first boot sound has
gone. During the opening it gives an error message something like that:

"Sound server informational message:
> Error while initializing the sound driver:
> device /dev/dsp can't be opened (No such device)
> The sound server will continue using the null output device

Any suggestions will be highly appreciated.
Best regards.