"mshtml.HTMLWindow2Class.document " throws System.UnAuthorizedAccessException.

I am using mshtml.HTMLWindow2Class.document property to check the state of the web page. But I kept get the following exception:

System.UnAuthorizedAccessException.

Anybody know how to fix it? I 开发者_JS百科think maybe some permission is not configured correctly for mshtml, but I donw' know the detail steps to check and configure it.

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Maybe I could put it this way:

If a COM component lacks some permission, how could I grant it?

Thanks!