Whenever I select an audio clip in PPro CS5, and select 'Edit in Audition', the file is created, and Audition starts, but then fails with the 'Adobe Audition could not find a supported audio device.' error. Easy enough workaround, I can just OK the error, then close PPro, open Audition and edit the file that was created from PPro without any difficulty. It seems as if PPro is bogarting my audio device, preventing Audition from access. My version of Audition is 3.0.1. My audio device is onboard NVIDIA High Definition Audio.
I would go into Audition's Preferences and check all of the settings, especially the ASIO settings.
You might want to also post to the Audition Forum, as most Au-users here are only scratching the surface of that program, and the folk on that forum might see things quickly, that we may miss entirely.