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Thursday, February 26, 2009

Opening/Unblocking .CHM Help Files on Windows XP SP2 or Vista

In one of my coding projects, I created a .chm help file, and loaded it to the server. However, it didn't survive the round trip: when I attempted to open a downloaded copy in Windows Vista, I saw the following message (click to view full size):

I did not for certain what was wrong, though I suspected it was some kind of security issue on Vista. I was correct.

.chm files that have been downloaded from the Internet are considered a security risk on both Windows XP and Vista. Bill Evjen blogs about the solution here; the solution, as he reports, is simple. Just right-click the file, select Properties, and then click Unblock (click to view full size):


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