"The Supplied Credentials could not be validated.Either they are invalid or there is a problem with the authentication system. Try again or contact your help desk." Error in Citrix

When we try to access any applications with citrix web interface, we ll see the above error after providing our username and pwd. If yes, follow the below procedure. If still not working, readd the machine in which presentation server is installed to the same domain.
1. Use the Services Control Panel to stop the Citrix XML Service.

2. At the command prompt, type ctxxmlss /u to unload the Citrix XML Service from memory.

3. Type ctxxmlss /r8080. This forces the Citrix XML Service to use TCP/IP port 8080.

4. Restart the Citrix XML Service in the Control Panel.

After restart, open the Management Console for MetaFrame Presentation Server, go to your server’s Properties > MetaFrame Settings, and verify that the specified port is seen in the TCP/IP port of the Citrix XML Service section.