Certificate Issurer not Recognised

[velinion]

Installed Ubuntu on my girlfriends computer, but am having an odd problem. On some websites, I get the following error when setting up a secure (https) connection in Firefox. (Have not tested in other browsers.)

The certificate is not trusted because the issuer certificate is unknown.

If I go to Add Exception, then View Certificate, the top of the certificate window displays the following error in bold.

Could not verify this certificate for unknown reasons

The certificate I pulled this off was for a bank, and issued by Verisign, within a valid date range, and works on this computer under windows (duel boot), and other computers (tryed on mine in both Win and Linux with no errors.)

So far, I have tried

sudo apt-get install --reinstall ca-certificates
sudo apt-get install --reinstall firefox

without any improvements.

Any ideas?

EDIT: Sorry, realize I posted this in the wrong section of the forum: that's what I get for posting at 1AM I guess. Could a passing mod please move it to an appropriate location? Thanks!

[cdenley]

Are you sure the entire certificate is exactly the same as the one which is used by the other systems which don't complain about it?

[www2]

I heft the same problem with Verisign certificates