I just did a fresh install and flash isn't working in firefox. I formatted the main / drive, started with a new username so that there aren't any conflicts with past preferences.(flash was a problem before)
I only made a handful of changes as follows:
In installed policycoreutils-gui so I could disable SELinux, because I've seen it conflict with flash before.
I changed the screen resolution to 1152x864.
I rebooted twice - once inbetween the install of policycoreutils and again after installing mozilla and the flash plugin.
What do I need to do to get flash working?