I have a remastered compactflash version of knoppix 3.4 (so switching to a newer version of knoppix is not an option)

When I boot knoppix, my onboard soundcard (AC-97) is recognized and configured. If I boot into single user mode, my soundcard is functional, since typing the following command at a prompt enables me to hear something:
cat file.au > /dev/dsp (also I can redirect to /dev/audio)

However, once booting into KDE 3.4, the soundcard is no longer accessable. typing the above command at a prompt returns "device or resource busy"

How can I keep KDE from causing a conflict with my soundcard?