Which version of outlook are you using?
I wasnt aware that any of the normal connection methods to rogers or yahoo, required certificates (other than if connecting via web access)
Under your account settings, what servers is it using to connect to your rogers account?
This may be easily solved by a change of server connections.
(Oh, aslo, are your windows updates up to date? There was a certificate update thing a while back, which may have changed/corrected how some things connect with specific certificates.