Does IE raises error if the code sign expires?

We have a full trust XBAP code written with .Net Framework 4.0 signed with a certificate from Versign which expires on October 24, 2014. It is not time-stamped. I am wondering what would happen when the code sign expires. I have researched through internet the answer seems to be both yes and no. Some say the application is OK since when it is signed, the certificate was valid and others seems to say it is flagged as untrusted and IE will raise error or some kind of popup message. We did purchase a new certificate and signed with it, which is to be delivered to the customers. But, I do not know what I should tell our customers what will happen when if they don't use the application with the new code sign.

Do you guys have any idea? If any error is raised, what kind of error is shown?

Thanks.