Cannot view Help in Designer

I’m trying to find out if anyone else has encountered this problem - I think it is an installation issue with Designer. In both Designer 7.1.2 and Designer 7.2 (which I had installed on PC today), I cannot use the Help utility - either online, dynamic, etc. I can get the Help TOC, but any attempts to access a specific help topic or page results in the error: This page cannot be displayed. The url you are looking for is currently unavailable… The error also says Access Denied.
The file does have the appropriate html files for Help, and it’s located in the correct spot. I have admin privs on my PC, and have full privs on the Designer folder for the installation. I’ve been told there is an xml file somewhere that references the file and extracts the requested html Help page. Possibly that’s been corrupted or lost somewhere?
Has anyone else experienced something like this? Any ideas or solutions?