FreeBSD firefox users, the linuxpluginwrapper (/usr/ports/www/linuxpluginwrapper/) doesnt work completely, you can remove it completely, but as you may well need flash and things like that the best thing is to remove the non working (read useless) part of the linuxpluginwrapper
edit all the references for the Acrobat5 plugin from your /etc/libmap.conf file and also do the following
cd /usr/X11R6/lib/browser_plugins/
mv nppdf.so nppdf_so.old
cd /usr/local/Acrobat5/Browsers/intellinux/
mv nppdf.so nppdf_so.old
cd /opt/mozilla/plugins/
mv nppdf.so nppdf_so.old
you can of course rename them to something else or remove them, but if it starts workin again then you can just rename them back 😉