HttpWebRequest and Response Issues - vb.net

Question

So i have this class that I use for HTTPwebrequests. In this instance of my program I'm posting some data as well as a cookie. Now heres the really wierd part. I use fiddler to sniff headers and monitor the traffic of my program in testing. If fiddler is open this function works just fine. If fidler is closed whenever I go to post anydata the operation times out. It always does this. No matter what I do. Can any one shed some light on this as I'm pulling my hair out in frustration.
Public Function Send(ByVal URL As String, _
Optional ByVal PostData As String = "", _
Optional ByVal Method As HTTPMethod = HTTPMethod.HTTP_GET, _
Optional ByVal ContentType As String = "", Optional ByVal Refer As String = "")
Dim Request As HttpWebRequest = WebRequest.Create(URL)
Dim Response As HttpWebResponse
System.Net.ServicePointManager.Expect100Continue = False
Dim SW As StreamWriter
Dim SR As StreamReader
Dim ResponseData As String
Dim a As New CookieContainer()
' Request.Proxy = New WebProxy("173.234.250.164", 3128)
' Prepare Request Object
Request.Method = Method.ToString().Substring(5)
Request.CookieContainer = a
' Set form/post content-type if necessary
If (Method = HTTPMethod.HTTP_POST AndAlso PostData <> "" AndAlso ContentType = "") Then
ContentType = "application/x-www-form-urlencoded"
End If
'Set User Agent
Request.UserAgent = ("Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.1; WOW64; Trident/4.0; GTB6.6)")
'Set Refer
If (Refer <> "") Then
Request.Referer = Refer
End If
' Set Content-Type
If (ContentType <> "") Then
Request.ContentType = ContentType
Request.ContentLength = PostData.Length
End If
'Set Cookie If Given
If (Cookie <> "") Then
Request.Headers.Add("cookie", Cookie)
End If
' Send Request, If Request
If (Method = HTTPMethod.HTTP_POST) Then
Try
Debug.Print("Inside Post")
SW = New StreamWriter(Request.GetRequestStream())
SW.Write(PostData)
Debug.Print("Wrote Post Data")
Catch Ex As Exception
Throw Ex
Finally
SW.Close()
End Try
End If
' Receive Response
Try
Response = Request.GetResponse()
For Each cook As Cookie In Response.Cookies
Cookie = Cookie & cook.ToString() & ";"
Next
Debug.Print(Cookie)
SR = New StreamReader(Response.GetResponseStream())
ResponseData = SR.ReadToEnd()
Catch Wex As System.Net.WebException
SR = New StreamReader(Wex.Response.GetResponseStream())
ResponseData = SR.ReadToEnd()
Throw New Exception(ResponseData)
Finally
SR.Close()
End Try
Return ResponseData
End Function

Answer 1

You're never disposing the HttpWebResponse - which means the connection is going to be held open. You should use a Using statement for Response. (I'd also suggest that you declare variables as late as possible, rather than declaring everything at the top of the method... and that you use Using statements everywhere instead of closing things in Finally blocks.
Note that you're also closing SR in a finally block when it may not be set - if some exception you weren't expecting is thrown, your attempt to close SR may throw a NullReferenceException. Personally I'd treat the two StreamReaders (one in the success case and one in the failure case) separately.