I had this error, and another bizarre browser bug that I was unaware of until both caught me totally by surprise. First, try the simple stuff. If you've imported contacts from google or another provider, but your contact primarily uses yahoo mail as you do, delete the imported contact data entirely, (in yahoo ONLY) Then add your contact back using only their yahoo email address. Next, in Win 7, check your "default mail client" in your control panel. Until today, I thought Windows did this automatically. It doesn't. After selecting your prefered mail client from the available options, you are not yet done. Click on it and you may see a dialog box with a blue link for your mail client's site. Mine was Windows Live. You'll be directed to a download page. I hesitated because I was puzzled, but finally, I downloaded. Follow whatever prompts you get along the way CAREFULLY. Remember, this funky process works, but will not be fully activated until you REBOOT. So be sure to do that. Open Yahoo Messenger. If no one is on, just pick someone and pretend that you're going to SMS them, or do whatever triggered the error before. Oh, no more error(s)? Good, you're done. Enjoy My sincere thanks to the user who helped me. Yahoo isn't the problem. It's Windows folks.