We had the same problem and found that Verisign G5 root certificate has to be
added to the local database NSS DB. To do this follow the steps below:
1) Download entire "Verisign root package" from
http://www.verisign.com/support/roots.html
2) Extract to a particular folder and add "VeriSign Class
I posted in the Mozilla Help Forum with more details than I did here but
still didn't find a solution. I finally tried overwriting cert8.db and
secmod.db from one of the other two computers that were still OK. And
that cured it. Of course it will happen again as it has to all three
computers so
