That is when I noticed when running from terminal Firefox is displaying a lot of missing shared object) files, like this :
LoadPlugin: failed to initialize shared library /home/aaaaaa/.mozilla/plugins/libflashplayer.so [libplds4.so: cannot open shared object file: No such file or directory]
LoadPlugin: failed to initialize shared library /usr/lib/adobe-flashplugin/libflashplayer.so [libplds4.so: cannot open shared object file: No such file or directory]
The idea is that in some way all the soft links to the *.so.1d or *.so.0d files are deleted. So I had to recreate them. The following link helped a lot to that end.
Issuing the following command is all that is needed so get back flash in Firefox.
ln -s /usr/lib/libnspr4.so.0d /usr/lib/libnspr4.so;
ln -s /usr/lib/libplds4.so.0d /usr/lib/libplds4.so;
ln -s /usr/lib/libplc4.so.0d /usr/lib/libplc4.so;
See also http://kheyali.blogspot.com/2009/09/audio-problem-in-dell-laptop.html