Back up all data.
Launch the Keychain Access application in any of the following ways:
☞ Enter the first few letters of its name into a Spotlight search. Select it in the results (it should be at the top.)
☞ In the Finder, select Go ▹ Utilities from the menu bar, or press the key combination shift-command-U. The application is in the folder that opens.
☞ Open LaunchPad and start typing the name.
From the Category list in the lower left corner of the window, select Certificates. In the list of certificates on the right, there may be one or more have a name that begins with "VeriSign". Export each such certificate by dragging it to the Desktop, then delete it from the keychain. You'll be prompted for your administrator password. If there are any expired certificates, regardless of name, delete them without exporting.
Next, select My Certificates from the Category list and do the same.
Test. If all is now well, back up again, then delete the certificates you exported to the Desktop.
It's been reported that an obsolete version of an application called "Cyberduck" may add Verisign certificates to the keychain. I can't confirm.
