.NET UploadHandler.ashx Issue

We are experiencing an issue uploading a document for employess running Windows XP and Internet Explorer 8. This works just fine for everyone on Windows 7 and Internet Explorer 8.

The vault control successfully fires our Upload Handler but there is a line of code that is failing causing the progress bar to just keep loading becuase the Application Property CurrentSize is never updated telling the control the file has finished.

The function is:

public void ProcessRequest(HttpContext context)
   byte[] filecontents = null;

   HttpWorkerRequest workerRequest = (HttpWorkerRequest)context.GetType().GetProperty("WorkerRequest", BindingFlags.Instance | BindingFlags.NonPublic).GetValue(context, null);
   if (workerRequest.HasEntityBody()) //Returning False for XP User

Any Ideas?