On Fri, 26 Jul 2013, Yaron wrote:

> Ok, does Flash constantly crash for you guys, or is it just me?
>
> Just in case it IS just me, I'd like to figure out if it's Ubuntu, Firefox or 
> the multiple monitor thing that's making it crash.

Doesn't crash for me on two monitors. Ubuntu 13.04 Firefox 22.0.

Also want to add this for anyone who hasn't seen it.
Dual monitors have been with both NVIDIA and ATI cards
Idea to try: 
rm -rf ~/adobe
  to get rid of the cache  ???

Also!
http://christianiversen.dk/2013/07/flash-is-terrible-how-to-fix-fullscreen-flash/

TL;DR;
If you want fullscreen flash to stay full screen while you go to a 
different monitor or a different virtual desktop you can hack the flash 
library:
sed -i -re s/_NET_ACTIVE_WINDOW/XNET_ACTIVE_WINDOW/ \
     /usr/lib/flashplugin-installer/libflashplayer.so


Gerry