Shows an error message Immediately “Connection was reset while page was loading” asp.net and firefox

I have a asp.net page to update Employee details in sqlserver database and upload up to five files in to folder through Web services.It is working fine,
but after 1 or 2 hour,When we try to update records with file upload it shows an error error message.
 "The connection was reset. The connection to the server was reset while the page was loading
  The Site could be Temporarily unavailable or too busy try again in few moments
  If you are unable to load pages,check your computes network connection
  If your computer network connection is protected by firewall or proxy,make sure that Firefox is permitted to access the web"
Can any one help to solve this issue?
Here is the code i used in project.
Stream fs = FileUpload1.PostedFile.InputStream; BinaryReader br = new BinaryReader(fs); Byte[] bytes = br.ReadBytes((Int32)fs.Length); entite.File2 = bytes; entite.FileNa ...