Qt Assistant in 4.6 not rendering .qch files rendered properly in 4.5.1

Qt Assistant does not display a .qch file that is rendered properly by Qt/Windows 4.5.1.

Steps:

1) Launch Qt Assistant
2) Preferences > Documentation > Add
3) Navigate to attached .qch file and add to documentation set
4) Attempt to open documentation in Contents

Expected: Appropriate HTML should appear in the active browsing tab as in 4.5.1
Results: HTML views remain blank for all entries in Contents tab; no errors printed to debugger console

Note : I checked the problem in which it's now forbidden to use "_" chars in the adress of the documentation... It's not working anyway...

We've been using Qt Assistant to display our documentaiton for ages and it suddendly stopped working... I changed the namespace and virtualFolder which contained underscore caracters but it still won't work...

I added a simple project that I've done with qhelpgenerator (Qt 4.6). When i load the file "assistant_fr.qch" into QtAssistant (4.6) nothing appears in the content part of the window ! When i'm using 4.5.1 everything is being displayed properly !