When I go into Itunes the next day, all my podcasts are gone. I have XP, so how do I fix that?

I have searched the web for "missing podcasts", "podcasts gone" and all I get is postings to blogs where the blogger says his/her podcast is missing this week cuz they didn't make one! I can't believe that searching for those phrases didn't turn up a single hit on a discussion board or something about this problem...