Uploaded file size is 0kb when uploading a file bigger than 100kb

When I try to upload a file that is 150kb (or bigger) then the file gets created on the server but its 0kb big but when I try to upload a file that is 40kb then the upload works fine (onto the server)

Any ideas.

Incase your wondering. I have set the web.config file...

<httpRuntime maxRequestLength="20408576" executionTimeout="6400" maxQueryStringLength="2048" enableHeaderChecking="false" />

I've also set...

  <system.webServer>
     <modules runAllManagedModulesForAllRequests="true">
     </modules>
    <security>
      <requestFiltering allowDoubleEscaping="true">
        <requestLimits maxAllowedContentLength="52428800"></requestLimits>
      </requestFiltering>
    </security>
  </system.webServer>

I have also set all the permission to that folder.

Please note that there is no error messages anywhere.