Sadly, I haven't solved the problem yet but I have found a way to get the Aardvark to work again after this problem happens. I'm not running any other interfaces like you are and I do have my on-board sound disabled and Windows sounds turned off. My DAW worked fine for years and then, some time ago, it started doing what you are describing, though not upon starting Sonar, only after a Sonar crash of any sort (which also was not a problem for several years). I, too, have an Aardvark Q-10 and am using Sonar PE 5.2.
I had been running this setup for YEARS and all of a sudden in Oct/Nov this started. I've turned off Windows Sounds and nothing else is running. I am using the updated drivers for my mobo (NF7-S) and using the patches for SONAR 5. I have reinstalled XP probably 5 times (SP2 or 3) and get the same results. BOTH cards are 24/96 so not sure what the problem is. I have tried with different projects, also changing from 24/48 to 16/44.1. When I launch SONAR 5 PE I get the message 'The following driver(s) either do not support the current audio format, or are in use by another application.' The audio engine also does not start. I have an Aardvark Q10 and a buddy's FirePod and I get the exact same results. I've been pulling my hair out for a couple months now trying to solve this so I hope someone can help.
