Prompting for apple ID login on iTunes launch

Hopefully someone can point me in the right direction, as I've tried to find the right thread for this without succes. Every time I launch iTunes, I am prompted to login to my apple ID to check available downloads, even though I have "always check for available downloads" deselected. It also did this when I had the option selected. I've had this problem on-and-off for months, not really sure what to do about it.