Whoops. Let me reformulate my post:

I completely agree with Caroline Bauer.

In my humble opinion, you're barking up the wrong tree. The 'problem' is lexical, not grammatical.

"I'm lovin' it" means nothing else than "I'm ENJOYIN' it very much".

Which works just fine in the progressive. This doesn't break a grammatical rule, it's a new meaning for the word 'love'.