Forgot to mention, we have Exchange 2007. The user use Outlook 2007 on XP. Both remote desktop connection and Citrix are on XP also. She is given the same permission on the particular calendar under the public folder. However, we cannot even try to access to that calendar because Public Folder is invisible under her logon.
Next time add additional info under discussion, not answers please. Thanks. Check the mail store she is in and make sure there is a public folder associated with the mail store.