Everything was working until a power outage caused a server crash (as far as I know...).
Cannot access OWA internally or externally.
BPA does not show any errors.
Opening IIS I can browse to my antivirus control panel, but cannot open SBS Web Applications or any of the sites under it. So IIS appears to be working.
If I click on Exchange (Under SBS Web Aps) I get the error message:
Could not find a part of the path "\\.\BackOfficeStorage\mydomain.local\MBX".
The problem initially showed up as a failure in activesync.