I am a bit of a noob so my question may be simple for someone to answer.  I do give kudos and follow up on threads for those who care about that. 

Basically my issue is this:

I have a VF page, custom tab and APEX class that is meant to allow a user to go to the tab and see a related list of cases for their contact record.  Their contact record is under an account tha tthey are not supposed to have access to so I thought having the without sharing keyword in the class would work but I am getting an error when I go to that tab as that logged in user.  Since the class operates at the system level why am I getting error messages based on the sharing settings?  Any thoughts would be appreciated.  (Oh, the code works because when I go to that tab as the admin it works as intended)

Below is my VF page and Class.

<apex:page standardController="Case" extensions="CC_getContact">
    <apex:tabpanel >
        <apex:tab label="Cases">           
                <apex:relatedList list="Cases" subject="{!theContact}"/>
                <style type="text/css">.actionColumn {display:none; visibility:hidden}</style>          
        </apex:tab>
    </apex:tabpanel>

</apex:page>

//This Class is used to get the contact record of the current logged in user for use in a visualforce page.  


public without sharing class CC_getContact {
  public Contact theContact { get; set; } // You can use theContact on your page.

  public CC_getContact(ApexPages.StandardController controller) {
    Contact[] c = [SELECT Id FROM Contact WHERE FirstName = :UserInfo.getFirstName() AND LastName = :UserInfo.getLastName() and Email = :UserInfo.getUserEmail()];
    // Make sure you select all the fields you need.
    if(!c.isEmpty()) {
      theContact = c[0];
    }
  }
}

The target profile has access to the tab and VF page.  Is there some permission issues posibly?