OWA Admin on IIS 5.0 Windows 2000 Member Server SP 4

I keep recieveing the following error trying to access the page:

Exception Details: System.ApplicationException: Access is denied.

Source Error:

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.
Stack Trace:

[ApplicationException: Access is denied.
]
System.Security.Principal.WindowsIdentity._Resolve Identity(IntPtr userToken) +0
System.Security.Principal.WindowsIdentity.get_Name () +71
System.Web.Configuration.AuthorizationConfigRule.I sUserAllowed(IPrincipal user, String verb) +100
System.Web.Configuration.AuthorizationConfig.IsUse rAllowed(IPrincipal user, String verb) +81
System.Web.Security.UrlAuthorizationModule.OnEnter (Object source, EventArgs eventArgs) +178
System.Web.SyncEventExecutionStep.System.Web.HttpA pplication+IExecutionStep.Execute() +60
System.Web.HttpApplication.ExecuteStep(IExecutionS tep step, Boolean& completedSynchronously) +87


Version Information: Microsoft .NET Framework Version:1.1.4322.573; ASP.NET Version:1.1.4322.573

I can make this run on a Windows XP SP1 PC with no porblems. Any Ideas?

An incorrect permission setting on the server is my guess.