For a year or two now I’ve experienced zombie message on my iPhone (3Gs, 4Gs, various versions of iOS). Maybe someday Apple will fix the problem.
The zombie messages cannot be deleted and there is no subject and no content. Sometimes while traveling, I’ll get 4 or 5 of these zombie messages.
There is no connectivity issues as the full-strength AT&T signal bars show. Once these zombie messages show up, they stick around, like electronic warts.
The only way they seem to go away is when I connect the iPhone to the computer.