Sven: Cache in this case doesn't matter, Flash Player settings (Hardware acceleration option) do – all is stored in ~/.macromedia/Flash_Player
Maybe you don't use the latest series of Nvidia driver (2xx), use older version of Flash Player (only 11.2 is affected) or you don't have libvdpau1 installed.
Sven: Cache in this case doesn't matter, Flash Player settings (Hardware acceleration option) do – all is stored in ~/.macromedia/ Flash_Player
Maybe you don't use the latest series of Nvidia driver (2xx), use older version of Flash Player (only 11.2 is affected) or you don't have libvdpau1 installed.