Sub Application_BeginRequest(ByVal sender As Object, ByVal e As EventArgs)
        ' Fires at the beginning of each request

        Dim context As HttpContext = HttpContext.Current ' 2
        Dim path As String = context.Request.Path ' .ToLower(); ' 3

        If AllowGZIP(path) Then
            Dim app As HttpApplication = sender
            Dim acceptEncoding As String = app.Request.Headers("Accept-Encoding")
            Dim prevUncompressedStream As Stream = app.Response.Filter

            If acceptEncoding Is Nothing Or acceptEncoding.Length = 0 Then
                Return
            End If

            acceptEncoding = acceptEncoding.ToLower()

            If acceptEncoding.Contains("gzip") Then
                ' gzip
                app.Response.Filter = New GZipStream(prevUncompressedStream, CompressionMode.Compress)

            ElseIf (acceptEncoding.Contains("deflate")) Then
                ' defalte
                app.Response.Filter = New DeflateStream(prevUncompressedStream, CompressionMode.Compress)
            End If
        End If


    End Sub

If WebLink is running on IIS 7 maybe check to see if it's running in Classic Application Pool Mode and not Integrated Application Pool Mode.

If it is running in Classic then at a command prompt reinstall .NET

For 32 bit:
"%windir%\Microsoft.NET\Framework\v2.0.50727\aspnet_regiis.exe" -i

For 64 bit:
"%windir%\Microsoft.NET\Framework64\v2.0.50727\aspnet_regiis.exe" -i