Error from VB excel macro code - msxml3.dll -2146697211 The system cannot locate the resource specif

I am using an MSXML.HTTPRequest object in a VB macro (excel) to communicate with an HTTP server. The problem is that it throws the following error intermittently.

msxml3.dll -2146697211 The system cannot locate the resource specified.

I noticed on my system that this happened when the network was down, but my client has complained of it happening intermittently on his machine. Given that his system has Windows 7 installed and it is working at times, I don't think it is an issue of the correct library not being installed. He has tried it on a few networks, but it still fails.

Function xmlHTTPPost(strURL, strData)  Dim objHttp  On Error Resume Next  xmlHTTPPost = ""  Set objHttp = CreateObject("Microsoft.XMLHTTP")  If Err.Number <> 0 Then      Err.Clear      Set objHttp = CreateObject("MSXML2.XMLHTTP")  End If  If Err.Number <> 0 Then      MsgBox "Error creating XMLHTTP object"      Err.Clear      Exit Function  End If  objHttp.Open "GET", strURL, False  If Err.Number <> 0 Then      Err.Clear      Set objHttp = Nothing      Exit Function  End If  objHttp.setRequestHeader "Content-Type", "application/x-www-form-urlencoded"  objHttp.setRequestHeader "User-Agent", "Mozilla Compatible (MS IE 3.01 WinNT)"  objHttp.Send  If Err.Number <> 0 Then      MsgBox "Error " & Hex(Err.number) & " sending to server:" & vbCrLf & Err.description      xmlHTTPPost = "ERROR: " & Err.Source & " " & Err.Number & " " & Err.Description      Err.Clear  Else      xmlHTTPPost = objHttp.responseText  End If  Set objHttp = NothingEnd Function

It's working perfectly on my box, which is a Windows 7 + Microsoft Office 2007 installation.

I have searched a lot online, and two reasons have been vaguely mentioned.

1. Network issues due to proxy or firewall. In this case it should never connect, not intermittently.
2. Library installation issue. Again, it shouldn't work at all but that's not the case.

I would really appreciate any help on this.

Answers

For now I was able to solve this by changing the method from GET to POST. The error was intermittent but fortunately it started showing up on my dev machine once, and changing the HTTP method to POST did the trick. It's very odd that should happen though, but it worked.