ITunes won't sync all of my apps

When I try to sync previously purchased apps, I get a message saying the computer is not authorized for some of the purchases and I am told to authorize the computer. When I go through all of the steps to do the authorization, I'm told the computer is already authorized. ITunes also doesn't show my purchases. I've emailed back and forth with Fritz from ITunes who said my problem is beyond his knowledge and I removed the SC file as suggested in other discussions. Anybody out there know what's happening? There seem to be a lot of problems like mine. Why hasn't Apple addressed this?