You can get Streams utility and run it with -d command-line switch for the file you want to unlock. It'll wipe out all alternate data streams from the file including the one responsible for Unblock button.

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>When I receive an XML attachment via Email and save it to a file the file is 'blocked'.
>If, for example, I open it in IE then I see the nested XML tags but cannot expand/collapse the nodes.
>If I look at the properties of the file in question at the bottom of the 'General' page it states:
>"This file came from another computer and might be blocked to help protect this computer"
>
>Question: How to "Unblock" such a file programmatically ?