iTunes won't login.

I am logged in on my iPad in iTunes.

I am logged in on apple.com on my computer.

I am logged in here on the forums with authentication on this computer.

Installed iTunes on this same computer and...my account doesn't exist. Screenshot #1 shows me logged in here and on apple.com (had to login to make a purchase)

No such login, iTunes keeps coming up empty.

Screenshot #2. Exact same info. And this is what itunes returns:

So if my itunes account exists on this computer, my iPad, apple.com, and these support forums. Why doesn't it exist on iTunes?

Any assistance appreciated.

Thanks.

And no, I would prefer not to reset my password in 4 different places just because iTunes is not working.