Once more a slight byte in the backside....
Remember those CHM files? Well, if not these are the older, yet still useful, HELP files (or as they are called now...compiled HTML help). It seems that in someone's paranoid wisdom? That someone decided to block by default content within CHM files. Yeah, I can see protecting yourself from bad CHM files (somewhere I remember that someone did create a virus within a CHM file...I also remember that a fix was put in place back in XP to resolve the issue). I guess Vista is a little scared of past problems, so it just assumes that everything is bad and locks it down.
So, got a CHM that comes up with no content? There is a fix...well a work-around. Right-Click the CHM file and go to properties. Somewhere near the bottom of the properties window on the general tab you should see a Security item along with a Unblock button. Now, if you trust the CHM content...press the Unblock button (and see all of the help file). As far as I can tell, you only have to do this once (per CHM file that did not originate on you computer).
Fun....
~cse