iTunes won't let me log in

Ok, I upgraded to 3.0 OS yesterday afternoon, and had no problems until last night. I went to upgrade my apps where applicable, but every time I try to log into the store it tells me my password is wrong. When indeed it is not. I'm logged in on my laptop and I can buy songs using my AIM screen name fine. But on my iPhone it won't allow me to. Anyone know how to fix this or getting the same problem?