Old versions of Cairgorm have a hard dependency on the Flex Framework, so there's not really any advantage to using it in a Flash project--you have to pull the whole Flex Framework along with it. If you're using Cairngorm, you're not bothered by Singletons (which IMO are extremely bad practice), so you might find PureMVC a viable alternative.
If you want to use a Framework that actively encourages good practice, try Robotlegs. It was designed from the ground up to work either in Flash or Flex, and it uses Dependency Injection rather than having everything reach out to touch some global state variable.
Thank you Amy,
I'll do look in Robotlegs. But meantime our project dependencies with Cairngorm framework and we've did a fair amount of work with it.
Searching over the forums in-line with this problem, I've found some this 'type' of problem (I emphasized on type because they're not actually meant with Flash IDE but Flex only), I've noticed a weird thing there's even. In multiple places I've seen people come out with not any probable alternative but by renaming some classes.
I starts inspecting my Flash project, and try to understand which probable class import cause this problem. I've found one class - which I whenever imports into the Flash its throwing the eorror, but not with any other Flex classes! Being curious, I've changed the name of the class keeping the same codes within, import it again in Flash, and voila! It worked! Weird! Isn't it?
But now I again can export SWC and run the Flash project without any trouble!