I keep being asked by iTunes for password and credit card verification, and getting warning emails I use iTunes (latest available build) on Windows 7 x64.

Whenever I buy apps for my iPhone, or download free updates to apps I already purchased, iTunes asks me to enter my Apple ID password, and my credit card confirmation number; everytime this happens, I also get an email from Apple saying "you purchased something from a device that has never been associated with your account, watch out because someone could be messing around with it".

I always used iTunes only on this computer, and I've tried logging out/in, and also unauthorizing the system and then authorizing it back again; but this keeps happening.

How can I fix this?
After going through various rounds of support calls and emails with Apple, there was no way to solve the problem. However, after some months, it just disappeared. I never actually found out what was causing it, probably some glitch on the Apple side.

Meh.