I have the / and /home on separated partitions. When I usually reinstall Ubuntu I mount old /home partition to restore old config, including installed flash plugin. At this time after reinstall I have installed ubuntu-restricted-extras and when i was getting a flash on web page firefox plugin install dialog spawned. I tried to install Adobe flash plugin and got "flasplugin-nonfree is installed". I closed firefox, removed flasplugin-nonfree, started firefox, tried to install plugin again. Package was installed, installer was downloaded from Adobe site, but firefox still asking me to install plugin.... even after restart.
No folder ~/.mozilla/plugins was created after installation. I've tried to install plugin several times and in the end I've deleted flasplugin-nonfree package, downloaded .tar.gz installer from adobe site and installed plugin manually.
My ubuntu-restricted-extras version is 10, from gutsy repository.
im having the SAME problem.....and it has been a while since this is happening....its a MD5 checksum error that happens when installing the flashplugin-