I've been having the same exact problem recently using Firefox 4.0b6. Wasn't able to register on this site earlier due to the lock-out so couldn't post my error log sooner. This is what it shows when I clear the log and then go to the Fast Dial page, hope it helps with a resolution.

Cheers

I actually don't have Stylish installed at all.

I have loaded this later beta Version of Firefox and can see there is a problem as you say with Fast Dial

Strangely the text underneath the logo can have a transparent background

This obviously suggest a need for a modification of the code

Thanks for letting us know...

Fast Dial itself still shows up for me as my home page and new tab page - it didn't at initial install, but resetting the home page and then changing it back to fast dial or something along those lines seemed to fix it for me.

i just downloaded fast_dial-2.23b3-fx.xpi and added
< em:unpack>true< /em:unpack> (delete spaces before em and /em)
to the install.rdf
and installed it on a freshly updated 4.0b7pre
disabled/enabled it and it works again just like before beta 5