If your playback list is complete, try enabling the motherboard audio, instead of using only SoundBlaster. See https://forum.audacityteam.org/t/system-sound-crashes-on-audacity-start/27419/32 .
Look on the ALSA / Ubuntu forums for Linux drivers for Audigy, if you have not already done so.
Try installing Pulse Audio Volume Control (pavucontrol).
Try not using Pulse (select the hw choice for Audigy in Audacity).
There do seem to be some Forum reports of Creative sound cards working correctly with Audacity on Ubuntu; perhaps search for those topics.
However, Creative never intended their cards to be used on Linux, so they may produce issues in some applications on Linux. Does Ardour have the same issue?
Gale