check URL

Make sure that ASP .Net application is running under a virtual directory. Set Virtual directory from IIS.

This would be due to the fact that your IIS's web root does not have the said /aspnet_client/system_web/1_1_4322/WebUIValidation.js file.

To resolve this issue, please follow these steps:
1. Open command prompt. (Start > Run > type cmd)
2. Run the following two commands:
Code:
cd %windir%\Microsoft.NET\Framework\v1.1.4322
aspnet_regiis.exe -c

1) Give machine_name\\ASPNET user permission
2) Disable Indexing service
3) Disable antivirus