When I tried the new Procmon 2.6, I couldn’t access the tool’s help file, which is a problem I have often encountered when downloading a Sysinternals tool. I have figured out now what went wrong and I thought I should note down the solution once and for all. I think, my blog is the best place for it because I am probably not the only one who run into this problem: The table of contents in the left plane is displayed correctly, but the contents pane only shows “Navigation to webpage was cancelled – What you can try: Retype address.”

I don’t know how I could retype an address in the Windows help interface; however, I don’t think that would work, anyway. The cause of the problem is related to Vista’s “Preserve zone information in file attachment” feature, which is a security feature that ensures that downloaded files of certain types can’t be opened. The help files of Sysinternal tools are compiled HTML, which Vista considers a threat.

There are several ways to convince Vista that opening a Sysinternals help file is relatively safe. The easiest way is simply to unblock the .chm file in its properties menu (see screenshot). I like the explanation there: “This file came from another computer and might be blocked to help protect this computer.” I suppose most of the files on my computer come from another computer. I am glad that Vista doesn’t consider them a threat as well.

If you don’t want to be bothered by this problem again, you can just disable this zone information-in-file-attachment thing using the Group Policy Object editor (type “gpedit.msc” at the Start Search prompt). The setting can be found under User Configuration | Administrative Templates | Windows Components | Attachment Manager. Don’t forget to run gpupdate /force on the command prompt if you want the setting to take effect immediately.

Daniel Petri has described this Vista feature in more detail and offers two more methods for disabling it.