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 [...]