Itunes will not let me purchase songs today?

I thought it was just the free Single of the Week, but yes, I am having this problem with other purchases as well. What's going on!?

What version of iTunes are you using? Look around the forums. There are many people here (myself included) with that problem. It seems that installing the latest version solves this problem. I haven't done it yet though.

Here's a different solution that has worked for some: https://discussions.apple.com/thread/4609900