WebBrowser Control fires "Access is denied" when I try to manipulate with IFRAME

[s.r]

Hello, my question is in WebBrowser control using.

I have some page http://somedomain.com/page1.html. This page includes
IFRAME with http://somedomain.com/page2.html. First html-page loaded
into WebBrowser control (and of course this pages loads second page
into iframe). When I try to manipulate with DOM of included iframe I
catch "Access is denied" error. So, it looks like cross domain
security exception but I have the same domain and protocol on both
pages. I found method IInternetSecurityManager::GetSecurityId which
can make this error. Is it default behavior of GetSecurityId? Or maybe
it could be another features of WebBrowser that I don't know.

Also I must say that this program is not mine. It has the proprietary
code (and I don't have opportunities to deeply analyze this) but I see
bug described above. And I suggest that I'll describe in detail error
for developers of program.

I'll be gratefull for any comments or opinions. Thanks in advanse.