iTunes connectivity: proxy authentication

Hi, i'm in a network with ISA firewall, and whenever i open itunes (windows), it asks for my proxy credentials. i enter them and click on "remember password", but in vain, it keeps on asking me multiple times. this happens each time i open itunes, it's frustrating! anyone got a clue? (sorry for writing under the "iphone" category, but couldnt find an "itunes" category)