Everytime I open Microsoft Office 2007, it gives me a certificate error. I've tried changing ports to see if that was the problem. I looked at the certificate and it's valid until 2015. https://www.dropbox.com/s/7nm4t6rzeo0b734/Capture.PNG?dl=0
Ok, I figured it out. I changed the incoming address from pop.mail.yahoo.com to legacy.pop.mail.yahoo.com and that fixed this error.