When compiling the Data tier classes for the Accounts module, I am warned that a null reference exception could occur at runtime because the code uses a variable before it has been assigned a value. The classes "User", "Role" and "Permission" all contain this warning.

Here is an exmaple of a function that makes this warning:

      Public Function GetAllPermissions() As DataSet
         Dim permissions As DataSet
         Try
            permissions = RunProcedure( _
            "AccountsGetAllPermissions", New IDataParameter() {}, "Permissions")
            Return permissions
         Finally
            If Not permissions Is Nothing Then
               permissions.Dispose()
            End If
         End Try
      End Function

The code will still compile, as it is a warning, not an error, but for my peace of mind, is there a better way to write those fragments of code so that this doesn't happen?

I can't see any code here that accesses a variable before it's been created. I assume vb.net initialize permissions to "nothing" in the Dim statement? If not, then you can set it to nothing after the Dim and see if that cures the warning.