I have one for you, I have had Music Match for several months, and all was fine. Yesterday when I tried to open MM got message "mm upgrade has been performed must restart computer" which I did, and I keep getting the same message over and over. went in and deleted all temporary files and cookies, and got rid of the message, but all I can get now is the small splash screen for a second and nothing else happens? using win XP home, and IE.

Sounds like a software error when the thing updated itself. Try uninstalling and reinstalling the software, making sure that you install the latest version, and turn off the auto update feature. If you don't want to do that then I'd suggest getting on to Yahoo Music Match tech support and telling them about it. You can do that here

It's got to be software error. I would suggest reinstalling it, and then upgrading it with it's latest security updates, and anything available.