Application pool issue in iis

See more:

C#2.0

C#

Hi.

while uploading files on server with parallel plesk panel,Application pool automatically stops and gives this error .

Error: Stop IIS application pool failed: websrvmng failed: The service has not been started. (Exception from HRESULT: 0x80070426)<br />
In Microsoft.Web.Administration module <br />
Exception type: System.Runtime.InteropServices.COMException<br />
at Microsoft.Web.Administration.Interop.IAppHostMethodInstance.Execute()<br />
at Microsoft.Web.Administration.ConfigurationElement.ExecuteMethod(String methodName)<br />
at Microsoft.Web.Administration.ApplicationPool.Stop()<br />
at IIS7ApplicationPool.startStop(IIS7ApplicationPool* , Boolean start)<br />
at IIS7ApplicationPool.stop(IIS7ApplicationPool* )

What is the reason for this one.
ans are appreciated

Thanks a lot in advance:-)