I had the same issue where it would hang and not generate thumbnails for HTML . I ended up un-installing any beta Firefox web browsers and xulrunners that weren't with the regular Ubuntu repos, now everything works again. I also tested the OP link and it worked fine.
I had the same issue where it would hang and not generate thumbnails for HTML . I ended up un-installing any beta Firefox web browsers and xulrunners that weren't with the regular Ubuntu repos, now everything works again. I also tested the OP link and it worked fine.