Probably not much help but...
It looks like somebody added an account to your system with some sort of intrusion script that he/she was not familiar enough with to properly configure. Or, some program you installed added it that so it could access system files or permissions for something devious, if you are sure that that should not be there, then write it down, delete it, and if it breaks your favorite proggy then that proggy proably put it there.
This might not help much but it is what came to my mind when I saw it.