CoreAudio error (-10202)

Hello! I've had my Mac Mini for a few weeks, and
until yetserday everything was fine. Here's what's
wrong:

No start up sound

Can't access sound volume from System Prefs window
(sound bar is grayed out and the mute is on and
un-clickable).

Used sound button on keyboard -- no icon onscreen
when sound up or down is pushed. When mute button is
clicked on keyboad icon flashes on, but sound still
"muted".

Sound icon is up in menu bar, but disappeares when
you click it.

First sign of problem: no sound in Quicktime.

Opened iTunes -- iTunes will not play anything- even
from the Store.

Opened Garage Band got these two errors:

1st was "error code -2 returned by Core Audio
driver"
so I restarted the machine, did the unplugging of
everything, etc.

2nd was (and still is) "CoreAudio - selected Driver
could not be found (-10202)"

Did the firmware upgrade. Unplugged and replugged.

No sound in anything...

help....


Mac Mini Duo Core 1.66
intel Mac OS X (10.4.6)