iTunes Store problems

Hey guys,

I've been having huge problems with my iTunes and I dont know how to solve them. First of all, I have two accounts for 2 different countries, one American and one European because I lived in the US for a year. I recently signed in to my American account because I wanted to see what was new in the American iTunes Store. But now I just can't sign back into my European account OR switch back to the European store! Whenever I click "Sign Out" from my American Account, iTunes freezes; same when I try to switch to another iTunes Store. Whenever I open the iTunes after that, its just frozen from the beginning and I cant do ANYTHING. Also on my iPhone the store is just blank; or it says "your request could not be completed". I dont know what to do anymore, anyone having any ideas what i could do?? I always used to switch between stores, and now all of a sudden it doesn't work anymore. Did iTunes disable that option?! Cuz as long as Im in my american account I can do whatever I want in the Store and iTunes doesnt freeze; that only happens as soon as I try to switch. I hope someone can help me, otherwise I might just have to delete iTunes and all that comes with it from my PC.

Thanks