I don't understand what is not working. Can't you open the topics assigned to books? Won't the books expand? Can you please tell us what exactly is happening and what you expect to happen.
You can do a quick test for the browser with another computer. Try opening the help from another computer. You can also let a collegue log in to your computer to open the help.
The TOC books work fine until you click on a topic (you can open and close books all day). Once you click on a topic, however, you cannot open any more books, nor can you close the books that you already opened.
Clicking on a topic from the TOC continues to work even after the close/open book problem surfaces (assuming you already opened a book to expose topics)..
I did wonder if it is a browser setting, add-on, or something similar, as it works fine on a co-workers machine. I have made adjustments to my browser settings, but still have the problem.
I can view other webhelp output without these problems.
I can even generate new webhelp and then view it without problems. The only thing I can see that is different from my problematic webhelp project and other webhelp projects is that the problematic project is generated in RoboHTML and the others are generated in RoboHelp for Word (version 8 for both).
Have you tried removing all your browser history, browser cache etc? It may be there's a fault script left over in the browser's cache.
Do you perhaps have Chrome Frame installed for your Internet Explorer? What other add-ins do you have installed?
I've seen some problems with IE before where it was a problem with the user profile. Having ICT delete the user profile from the local pc solved the problem. But it means losing more than browser settings. What happens if a co-worker logs on to your pc with his own credentials. Does the help work then?