I manually deleted diginotars certificate on my laptop (as per mozilla's instructions), and then copied the cert8.db file from within the firefox directory to the phone. Going to https://www.diginotar.com/ presented me with an invalid certificate, so it's working. Edit: You could also use certutil to remove just the one certificate, you'll have to copy your cert8.db over to a computer that can run the certutil program, and the copy the database back over.