Hi ,
As I understand compound path is several paths compound together by one of the combination method(add,union,punch,etc).

Now I copy a shape from Photoshop , I paste into illustrator cs 2 , it paste it as a compound shape (because the shape is a car side which have windows punched in it). Now I want to perform some punching(with pathfinder) on that shape but illustrator cannot do it, maybe because its compound shape.

What should I do? Should I convert this compound shape into a path? If I do so how? And some more information about compound shape vs path can be helpful as well.