Here're the steps:

• Step 1. Create a system user e.g. ForASPNET on the machine which hosts the ASP.NET application. (I created domain user e.g MyAccount)
• Step 2. Grant the same permissions like ASP.NET built-in account Network Service. You could start the Visual Studio Command Prompt and run this command "aspnet_regiis -ga ForASPNET".(I used domain user e.g MyAccount)
• Step 3. Create a system user in the shared server with the SAME name and password.(I used domain user e.g MyAccount)
• Step 4. Grant the permissions to the shared file to the user ForASPNET. (MyAccount)
• Step 5. Set the Identity as ForASPNET (MyAccount) in the ApplicationPool which the ASP.NET application is running under.(

  • Right click a specific ApplicationPool and choose "Advanced Settings".
  • Click the Identity and choose "Custom account".
  • Set the new created account.)
     
    For me works fine.
    Reggards,
    Bart