This Connection is Untrusted
You have asked Firefox to connect
securely to www.google.com, but we can't confirm that your connection is secure.
Normally, when you try to connect securely,
sites will present trusted identification to prove that you are
going to the right place. However, this site's identity can't be verified.
What Should I Do?
If you usually connect to this site without problems, this error could mean that someone is
trying to impersonate the site, and you shouldn't continue.
Technical Details
www.google.com uses an invalid security certificate.
The certificate is not trusted because the issuer certificate has expired.
The certificate will not be valid until 12/17/2009 7:00 PM.
(Error code: sec_error_expired_issuer_certificate)
I Understand the Risks
If you understand what's going on, you
can tell Firefox to start trusting this site's identification.
Even if you trust the site, this error could mean that someone is
tampering with your connection.
Don't add an exception unless
you know there's a good reason why this site doesn't use trusted identification.
My roommate can sign in on his computer without any difficulty. No other sites I've logged into in the past several days have exhibited this problem. AVG is and has been running, although attempting to update AVG results in a "your system time appears to be incorrect" (it is in fact accurate) alert message. The S&D Resident is also running and hasn't gone 'bing', and a Malwarebytes anti-malware quick scan revealed nothing malicious.
What's going on here?