The page A.com has 2 iframes B.com/page1 and B.com/page2. This is the code of A.com:
Instead of
parent.window.frames['iframe1'].SomeFunction(args);
use
parent.frames['iframe1'].SomeFunction(args);
You are allowed to traverse the frames
collection of any window that you can reference, but in this case you are trying to traverse the recursive window
property of parent
(which IS the window). This is not allowed.