I had a similar problem a few years ago, but similar on the most crudest level. I figured out that the page I was editing referred to a foreign language character set in the code. Or maybe it was the fact that it did not refer to a character set? Once I specified the Unicode, the little ™ guy was fine and showed up in all the browsers I tested.

I hazard to guess that the incorrect character set/lack of specification provides the wrong info to the Validator.