Same problem here. Had it for at least 24hrs. Like everyone else, I did everything the support site suggested apart from reinstall the OS.
Has anyone else tried checking their support package status here:
https://p2-buy.itunes.apple.com/WebObjects/MZFinance.woa/wa/iForgot?language-iso =en-us
After inputting my serial number and clicking 'continue', the page just hangs and hangs and hangs while the busy ticker cycles and cycles - left it 10 minutes then gave up and closed the page. Maybe the problem is a deep-rooted one that isn't only affecting itunes... Does it affect other contact with Apple too?
No problem using my itunes account from my ipod touch.
Apple: HELP!