Try here:
http://www.vortexofsound.com/drivers/drv_m39x.htm
These are the LATEST drivers for ALL Aureal sound cards which INCLUDE the Diamond Monster 300. Read it carefully. I THOUGHT I saw this page before!
If this helps PLEASE post back here. If not, I can always keep looking
This is the drivers that control the "loss" of sounds and problems with the Aureal cards. Good luck bud!!!
Sincerely;
Druadic