Action will crash when running virtual audio cable.
When running VAC action will crash with no warning, I use VAC to split audio channels so that I can isolate game sounds from things like teamspeak when I record. If i try to use Action it just fails to start. Dxtory and Fraps have no issues it would seem but action as I say cant start while using it.
I am not looking for support here on how to get it working though I guess that would be nice but more pointing out that the issue is there and that its perhaps something you might want to take a look at.
Information on VAC can be found here
http://software.muzychenko.net/eng/vac.htm