I thought I had searched before posting this, but found a recent (1/25) posting with a similar question.
The response was that RoboHelp does not support "favicons".
That posting is here.
I will close this posting as it is a duplicate question.
I checked out your Snippets section on your site and did not see anything on this for RH8.
Do you have the snippet number?
BTW - I tried replacing the whstart.ico file with one of my own (named whstart.ico but with my graphic) and it did not work.
I also tried editing the existing whstart.ico in my output directory and it did not work either.
I edited with SnagIt 9 Editor
Michael F Weart