ADFS Self-Signed Certificates are used for internal encryption and are separate from your SSL certificates. You can sometimes experience a situation where these internal certificates auto-rollover. when this happens it will bring CRM down.
Below is a blog that has a fix for this that seems to work if you follow all the steps to a T:
If you are having problems activating the SharePoint list component for CRM 2013 and SharePoint 2013 and the activate button is grayed out. You can try the method below if you didn't install SharePoint on a domain controller.
If you did install CRM 2013 on your domain controller like a lot of us Pre-sales guys used to do in the SP 2010 days, just slap yourself in the head right now. It appears you are beyond hope and need to break out your SharePoint server to another box that is not a domain controller. That's what I did today.... :(