Can't open signed (not encrypted) documents

[kwdavids]

I had this problem in Outlook 2003 and it persists in Outlook 2007.
It's happened in two cases:

1. I sent a signed (not encrypted) email to someone, who then replied
back. When I tried to open the reply, I got the error message:

"Your Digital ID name cannot be found by the underlying security
system". I can't read the mail or save the mail with Outlook.

2. I sent a signed (not encrypted) email that couldn't be delivered.
My email was returned as an attachment to the non-delivery message.
When I tried to open the attachment, I got the same error message:

"Your Digital ID name cannot be found by the underlying security
system". I can't open the attachment, but I can save it.

I can send emails fine. I can open other people's signed and encrypted
emails.

I tried opening the saved with the Cryptigo p7mViewer. It said the
attachment was "Not Encrypted" and "Not Signed" although the header
had:

Content-Type: multipart/signed;
protocol="application/x-pkcs7-signature";
micalg=SHA1;

No digital certificate seemed to be in the email text.

When I tried to open the attachment with the Outlook Web Access tool
and it said "This message has a digital signature, but it was not
validated. " I was, however, able to view the attachment (and the
other problem email). That's my workaround for now.