Portable version help file

The help file doesn't seem to work on the portable version of PSPad, at least for me. I get a message on the righthand side "Navigation to the webpage wa canceled". For other items, I get a message "The address is not valid". I can access the online help from the help file or the forums but not the builtin help.

I'm using PSPad 4.5.7 (2450) under WinXP. PSPad is located on a network volume. This computer has IE 7 installed, that might affect the help file. But it used to work just fine.

Right mouse over CHM file and in properties allow this help.
This is a operating system protection

Sorry, I can't see an item "allow this help". Possibly it's not on WinXP? We'll be migrating to Win7 in the near future BTW.

I found this, it seems relevant:www.helpscribble.com. Microsoft recently released a security patch that makes it impossible to view CHM files that are stored on a network drive (as opposed to CHM files stored on your own computer). It goes on to describe a registry hack. For myself, the online help is a good alternative

As I remember, on WinXP was necessary to make registry change to allow it.

Here is a problem description:
support.microsoft.com

Registry:
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\HTMLHelp\1.x\ItssRestrictions]
"MaxAllowedZone"=dword:00000001