XBooks actually quit working for me on Monday, August 7th due to QuickBooks seeing the certificate as invalid. Thus, not allowing XBooks to access the company file.
Apparently, Microsoft released a Windows update in about the last couple of weeks that invalidated a whole class of digital certificates. Because Windows deems this class of digital certificates as invalid, QuickBooks also sees it as invalid as well. This issue not only affects Synergration products but also other companies.