Authorization Error on WordPress 3.6 installation

Hi,
I installed and activated your plugin on my wordpress 3.6 application, but after that I have a fatal error and cannot login anymore:

Authorization Required
This server could not verify that you are authorized to access the document requested. Either you supplied the wrong credentials (e.g., bad password), or your browser doesn’t understand how to supply the credentials required.

Pls help!!!!!!!!

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