Ventrilo causes audiodg.exe in Windows Vista to explode and leak memory very quickly if you are using a Creative X-FI card and don’t have “Use Direct Sound” checked in settings.
Edit: It doesn’t seem to fix the problem entirely. Audiodg still grows but much slower than before. It grows about about 50-80mb a day, so it’s acceptable. I just restart the Windows Audio service to restart audiodg again once in a while.
Update: I have upgraded to Windows 7 and the problem seems to have disappeared. I suspect Vista is to blame.