Active Directory Certificate Services did not start: The Certificate Revocation List Period string is invalid in the registry ...

Active Directory Certificate Services did not start: The Certificate Revocation List Period string is invalid in the registry value HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\CertSvc\Configuration\%1\CRLPeriod.  Valid strings are "Seconds", "Minutes", "Hours", "Days", "Weeks", "Months" and "Years".