I get this message:
Cannot find the X.509 certificate using the following search criteria: StoreName \'My\', StoreLocation \'LocalMachine\', FindType
Try to use Certificate Manager (with MMC) to see installed certificates. Instructions for XP: manage certificates for a computer, probably similar with Vista and 7 as well.
I was having problems with service unable to find the x509 certificate, but by using the Certificate Manager I found out that "Install PFX" command from Windows Explorer had not installed the certificate at all! This was fixed by importing the certificate from Certificate Manager.