I’ve had some problems with Adobe Flash ever since I upgraded to Kubuntu Hardy Heron. Flash applets would come up in firefox as just a grey box sometimes. Sometimes I would come back to a previously-opened browser tab to find a Flash applet turned from a working video player (or whatever) to a grey box. Videos from sites like Youtube would often play but sometimes would start coming up as grey boxes until I restarted firefox. I tried uninstalling and reinstalling flashplugin-nonfree and nspluginwrapper with apt-get following some instructions I found online, but that never solved the problem. I tried the Adobe Flash Plugin 10 beta. I tried Opera. Opera wouldn’t load the flash files at all. I tried Konqueror. Konqueror would work more often than firefox, but still was inconsistent.

Here is my current solution that seems to have solved most all of the flash problems I was encountering. I removed flashplugin-nonfree. I removed nspluginwrapper. I removed Adobe Flash Player 10 Beta. Then I reinstalled just the flashplugin-nonfree package using aptitude instead of apt-get. I found this page was helpful in learning what to try. Here is a list of commands if you are having similar problems and want to give this potential solution a try:

sudo apt-get remove flashplugin-nonfree
sudo apt-get remove nspluginwrapper
sudo aptitude install flashplugin-nonfree