I have Outlook 2007 on Vista 32 bit Business. Recently I have this problem where if somebody sends me an encrypted e-mail I cannot decrypt and open it. When I try to open it I get the error message " your digital id name cannot be found by the underlying security system" . This happens with 2 different e-mail addresses which have their own separate digital certificates. I cannot read incoming encrypted e-mail on either of them. One digital certificate is a few weeks old and the other is 11 months old. Both have worked OK in the past. It seems to be an Outlook problem. It's like Outlook cannot find the private key installed. When I set up my e-mail account and digital cert on Thunderbird, everything works OK. I've tried to remove and reinstall the digital certificates on Outlook but I'm not sure if I did it right. I went into Internet Explorer and under Options/Content/Certificates and removed the digital cert. I couldn't find a direct way to remove it from Outlook. Then I reinstalled the digital cert from backup. It's didn't work, the problem still exists.