No active mixer devices available

I have a Dell Dimension 2400 with a Celeron processor
(about 2.4 gigahertz processsing speed) and 80 gig
hardrive. I got the PC in March and installed a
SoundBlaster Llive! card in one of the PCI slots. After
fiddling with the sound for a few minutes, it worked
beautifully. Last week, for some reason, there was no
sound and an error message came on the screen when I
tried to adjust the volume control saying there were no
active mixer devices available. I've tried reinstalling
the SoundBlaster card, reinstalling XP, reinstalling only
the audio drivers, and disabling the other sound option
(Soundmax). And yet, my computer sits as mute as Helen
Keller. Any advice? I did find a previous forum where a
guy from Dell told another sorry soul like myself to
uninstall all the audio controllers listed under the
Sound Video and Games Controller in the hardware manager,
shut off the computer and restart. What happens then is
that this Soundmax thing just automatically reloads
itself (I've tried disabling it and just reinstalling the
SoundBlaster drivers but I still get the message that no
audio mixer devices are available). Should I simply yank
my SoundBlaster card and try to produce audio with
SoundMax? (How the heck does one do that?) Disable the
SoundMax processor on the motherboard? (How does one do
that?) Plug my headphones into my stereo? Start taking
voice lessons again? Any advice would be greatly
appreciated!