I don’t know if it helps, but I had/have the same problem and found these:
wp-admin > images > menu-bits-fraught-reprise.php
wp-admin > instal-ranging-pummel.php
wp-includes > class-skill-indemnify.php
(I seriously hope I didn’t delete anything I shouldn’t, I’m a newbie)
This appeared one or two weeks ago, before the 3.5 WP update, on Godaddy host.
