Aide NRJ Chat

Bonjour,
depuis que je vais sur le chet, c'est a dire ya.. 9 mois environ quand je vais sur 'rechercher' ca me dit Server Error in '/' Application.
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No stylesheet was loaded.
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.InvalidOperationException: No stylesheet was loaded.

Source Error:

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

voilàà.. quelqu'un pourrait m'aider ? Merci :)