Ever since protected mode has been introduced with 11.2, I had troubles with it.
Within hours I found the protectedmode=0 entry in adobe's FAQs, but now (11.6) it doesn't seem to work anymore.
Making the sandbox mandatory is an incredibly bad idea, just in case the topic's title is answered with "Yes".
I can't and I don't want to use it since it *STILL* doesn't work properly as embeded flash windows *STILL*
steal windows focus (in other words, embeded flash media blocks all other forms and inputs!).