having problem with HelpExplorer
 

I am trying to read a chm book using HelpExplorer on my Fc4 machine. But sometimes after opening a new page, program stops working and CPU usage becomes 100% and only I can terminate HelpExplorer using command Kill. This error happens mostly when I open a large window or I press Ctr+ in order to zoom in the page.
Does anyone know how it's possible to get rid of such error or any other program which can open chm files? Everytime I find a good book its extension is chm so I get disappointed from reading it.

I successfully installed gnochm which is much better than HelpExplorer