[tlug] Sudden Certificates Problem

[CL <az.4tlug@example.com>]

At the same time I upgraded Xubuntu 9.10 to 10.04 on my 64-bit box, I 
began having a lot of trouble with sites I'd been visiting regularly 
being blocked by Firefox.  The usual message is that the site security 
certificates have expired ... with a warning that my connection may have 
been taken over.  There are quite a lot of them, particularly offshore 
ones including Yahoo and Google.
I am experiencing the same issue in the WIN version of Firefox running 
in a VirtualBox on the same hardware.
I have tested extensively but find no reason to believe that my machine 
has been compromised ... assuming I am asking the right questions and 
looking for the right things.
I do not see the problem in the x86 torrenting machine running on a 
separate connection (separate wiring, different phone number, different 
cable, modem, and router), but I have not tested aggressively.
Anyone else seeing the same thing?  Is this a result of a hacked machine 
or perhaps the recent upgrading of the WWW (can't find the reference 
offhand so this may seem bizarre if I have used the incorrect terms as 
expected).  Any suggestions on what other questions to ask?
--
CL