Comment 49 for bug 262693

I was also getting this error when starting firefox:
LoadPlugin: failed to initialize shared library /usr/lib/flashplugin-nonfree/libflashplayer.so [libnss3.so: cannot open shared object file: No such file or directory]

I was able to get both flash and sound to work by resolving that link:
$ sudo ln -s /usr/lib/libnss3.so.1d /usr/lib/libnss3.so

Then there were two more I had to resolve:
$ sudo ln -s /usr/lib/libsmime3.so.1d /usr/lib/libsmime3.so
$ sudo ln -s /usr/lib/libssl3.so.1d /usr/lib/libssl3.so