Warning: array_key_exists() [function.array-key-exists]: The second argument should be either an arr

Hello,

I am getting this error "Warning: array_key_exists() [function.array-key-exists]: The second argument should be either an array or an object in /home/birligi/public_html/wp-content/plugins/advanced-theme-switcher/advanced-theme-switcher.php on line 106" but that plugin is not installed, tried to install got error.