I dont know if this helps but I am going through a nightmare due to the recent security update on the Player 9 Update 3 (9,0,115,0), this has caused some weird non communication between my swfs on firefox and (I am told but haventy checked yet) on safari.
The weird thing is I downloaded the debugger player version for ie (which I think is the only way to get version 9,0,115,0 on ie at the time of writing this) and it all seems to work fine.
There is a release note link below:
This gives a lot of info about the effects which are supposed to be warnings at the moment NOT errors.
May be totally off base but hopefully it helps point you in the right direction. If it does, let me know if you manage to fix it.