Outlook 2007 Certificate Error (Yahoo)

I thought I created a thread but now cannot find it.  Here it is again:

I get a warning when sending email in Outlook 2007. I use Yahoo pop email and I have a paid Yahoo account. I never got this until I set up my new "Used" desktop a few days ago.  Same operating system...Windows 7 Professional. I didn't have this problem previously on my other PC.  It occurs when the progress dialog box switches to sending mail.

The dialog box title is "Internet Security Warning". 

I have attached a Word doc with screenshots.  As long as I click "yes" in the initial alert the email will be sent with no other issues. 

I just checked my old PC and it still doesn't happen on it.  I also double checked my email account settings. Is there a certificate on the PC somewhere? 

The reason I am searching the Symantec forums is because, when I click on the "view certificate" button, it shows a certificate path that has "Symantec Class 3 Secure Server CA-G4" in it. It also has "legacy.pop.mail.yahoo.com" in it.

Has anyone seen this before or having this problem, now?  Do you know how to fix it.  I did search on Yahoo email but didn't find anything.