Beryl not working with KDE + nvidia

[Marcelo Magno T. Sales]

Hi,

I have several FC6 boxes with nvidia cards in which Beryl does not work any 
more. When I select beryl as the window manager, it just starts to load and 
then immediately falls back to kwin.
These machines had beryl working in FC6 before, but I didn't use it for 
sometime and now it does work anymore. FC6 has been updated several times in 
these machines during this time and I have no idea of which update caused the 
problem.
How do I debug this?

Thanks,

Marcelo