Note that your System Details List shows multiple Flash plugins.
Shockwave Flash 12.0 r0
Shockwave Flash 11.9 r900
You can find the installation path of all plugins on the aboutlugins page.
You can check the Flash player installation folder for multiple Flash player plugins and remove all (older) version(s) of the plugin (NPSWF32) and (re)install the latest Flash player.
(32 bit Windows) C:\Windows\System32\Macromed\Flash\
(64 bit Windows) C:\Windows\SysWOW64\Macromed\Flash\
Do you only have this problem with the Aurora builds or with other builds like the current Firefox release or the beta version, assuming that you have other versions apart from a possible unstable aurora (alpha) build installed like you should?
Create a new profile as a test to check if your current profile is causing the problems.