[SalesForce] Name error in Visualforce Page

I am trying to create a simple VF page to view case using the Apex Page Parameters. However, I get the following error:

The name can only contain underscores and alphanumeric characters. It must begin with a letter and be unique, and must not include spaces, end with an underscore, or contain two consecutive underscores.

Here is the VF Page

<apex:page standardController="Case" extensions="CaseStatusFollowUpClass" sidebar="true" readOnly="true">
  <apex:pageblock >
    <apex:pageBlockSection title="Contact Information" columns="2">
      <apex:outputLabel > Contact </apex:outputLabel>
      <apex:outputText > {!CurrentCase.SuppliedName}</apex:outputText>
      <apex:outputLabel > Email </apex:outputLabel>
      <apex:outputText > {!CurrentCase.SuppliedEmail}</apex:outputText>
    </apex:pageBlockSection>
    <apex:pageBlockSection title="Case Information" columns="2">
      <apex:outputLabel > Subject</apex:outputLabel>
      <apex:outputText > {!CurrentCase.Subject}</apex:outputText>
      <apex:outputLabel > Created Date </apex:outputLabel>
      <apex:outputText > {!CurrentCase.CreatedDate}</apex:outputText>
      <apex:outputLabel > Priority</apex:outputLabel>
      <apex:outputText > {!CurrentCase.Priority}</apex:outputText>
      <apex:outputLabel > Status</apex:outputLabel>
      <apex:outputText > {!CurrentCase.Status}</apex:outputText>
    </apex:pageBlockSection>
  </apex:pageblock>
</apex:page>

And here is the extension class:

public with sharing class CaseStatusFollowUpClass 
{
  Public Id CurrentCaseId =   System.currentPageReference().getParameters().get('Id'); 
  public Case CurrentCase {get;set;} 
  public CaseStatusFollowUpClass(ApexPages.StandardController controller) 
  {
    System.debug('ID: ' + CurrentCaseId);
    this.CurrentCase = (Case)controller.getRecord();
    CurrentCase = [Select Id, CaseNumber, SuppliedEmail, SuppliedName, CreatedDate, Priority, Status, Subject 
                   From Case Where Id= :CurrentCaseId];
    System.debug('CurrentCase : ' + CurrentCase);

  }
}