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Just so you know, links to your admin won't show what you see since it requires authoriztion. I wasn't asking you to post a link but an image snap shot of what you see.
The define error is for modinfo language file shouldn't affect the tabs. I don't know what the xoopssecurity.php error is. Some one more advanced will have to address that.
Sometimes other modules cause global errors. Try un-installing the Myguestbook module -be sure to back up the data for this module before- then test the rw_banner again.