Firefox claims invalid security certificate for this site, but Chrome does not

I get an Untrusted Connection error when I visit this site to login into my GRE account, and I cannot add it as an exception, in Mozilla Firefox 4.0 on Ubuntu 11.04

When I visit the site using Chrome, I have no issues. Is this a bug in Firefox's certificate management? I'm using Ubuntu 11.04. I do not get this error in Windows' Firefox 4.0

I also received no error when I visited that site with Firefox on PuppyLinux. Looks like it may be one of Ubuntu's addons, tweaks or settings for Firefox. You might look into Manage Addons to see what's there. Also, make sure that SSL is not disabled. (I noticed it opened with "https://".)

Hope this helps.

If there's any "bug", perhaps it's the other browsers missing true discrepencies.

Just verify the site is valid, click "yes", and move on.

IMHO .. PSM

Gmail uses https and it doesn't have a problem with that. So I'm guessing it has something to do with that website's certificate. However it affects only Firefox 4.0 on Ubuntu 11.04. I don't think other browsers are missing any discrepancies because Firefox 4.0 on Windows doesn't complain when I access that site.

I'm unable to add the site to my list of exceptions as I've mentioned in the first post. When I click on the button, nothing happens.

Technical Details
          mygre.ets.org uses an invalid security certificate.

The certificate is not trusted because no issuer chain was provided.

(Error code: sec_error_unknown_issuer)

The certificate is definitely valid because it works for Chrome and even Firefox on Windows. There's something about the default Firefox that comes with 11.04 that causes this problem.

The site has this certificate: VeriSign Class 3 Secure Server CA - G2