If are using a 64-bit flavour of Linux, you’ll be surely affected by the npviewer.bin issue about random crashes of the Flash Player plugin in Firefox with a message like this in your /var/log/kern.log:
npviewer.bin[6489]: segfault at 418 ip 00000000f6034d36 sp 00000000ffaaf868 error 6 in libflashplayer.so[f5dc7000+b5f000]
Well, Adobe some time ago released a beta quality 64-bit native Flash Plugin player which seems to work quite well.
For example on a recent Ubuntu (mine is 10.04) these are the steps to use it:
1. remove the current plugin:
sudo dpkg --purge flashplugin-installer
2. download the 64-bit plugin from the Adobe site: http://labs.adobe.com/technologies/flashplayer10/square/
3. as root place the extracted file in: /usr/lib/firefox-addons/plugins/
4. restart your firefox and verify from "about:plugins" that it get loaded correctly
You are done! No more npviewer.bin segfault 
((enjoy))
Hoorah! Thanks very much, this issue has been bugging me for ages. At last, no more Firefox crashes! I presume this also covers Google Chrome browser?
Thanks again, David