We are seeing tons of these WINDOWS EVENTS being generated on our DNN Server (Windows 2003 running IIS 6.0). Can someone please advise on where we should be looking? We are running DNN Version 5.04.01 (26) 

Event Type: Warning
Event Source: ASP.NET 2.0.50727.0
Event Category: Web Event 
Event ID: 1309
Date: XXXXXX
Time: XXXXXX
User: N/A
Computer: XXXXXX
Description:
Event code: 3005 
Event message: An unhandled exception has occurred. 
Event time: XXXXXXXXX
Event time (UTC): XXXXXXXX
Event ID: c04931c87f56471994a4ee779c1ad097 
Event sequence: 1904 
Event occurrence: 828 
Event detail code: 0 
 
Application information: 
    Application domain: XXXXXX 
    Trust level: Full 
    Application Virtual Path: / 
    Application Path: XXXXXX
    Machine name: XXXXXX 
 
Process information: 
    Process ID: 3492 
    Process name: w3wp.exe 
    Account name: NT AUTHORITY\NETWORK SERVICE 
 
Exception information: 
    Exception type: NullReferenceException 
    Exception message: Object reference not set to an instance of an object. 
 
Request information: 
    Request URL: XXXXXXXXXX
    Request path: /Default.aspx 
    User host address: XX.XX.XX.XX
    User:  
    Is authenticated: False 
    Authentication Type:  
    Thread account name: NT AUTHORITY\NETWORK SERVICE 
 
Thread information: 
    Thread ID: 3 
    Thread account name: NT AUTHORITY\NETWORK SERVICE 
    Is impersonating: False 
    Stack trace:    at DotNetNuke.Authentication.ActiveDirectory.HttpModules.AuthenticationModule.OnAuthenticateRequest(Object s, EventArgs e)
   at System.Web.HttpApplication.SyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
   at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)
 
Custom event details: 

For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp.

Anyone?