I'm having a problem with iTunes where I can listen to previews and browse the store fine, but when it comes to signing into my account and clicking on certain buttons like 'redeem' it comes up with an error message that seems to change every time. It will say about the connection, which I know is fine as it all works ok on our other computer. It also says about an error in the iTunes store. I have uninstalled and reinstalled and I've done a system restore to a time when I knew the problem didn't occur and its still doing it. Any ideas?