5.5/2k3, can’t see some public folders

I am in mixed mode right now with one 5.5 Exchange server and one 2003 server. I have ADC setup and I am in the process of moving mailboxes from 5.5 to 2k3, but once I do that I notice that I can still see public folders from Outlook but there are 2 or 3 folders I cannot see. What coud this be?