I don't have any problem with the phrase, it's a metaphor, and one used for so long I don't think it has any more significance than being synonymous with "serious issues."

Incidentally, if anyone wants an etymology lesson, it's from the Greek δαίμων, which doesn't mean what we think of as a demon, but something or someone strange, which cannot be comprehended or understood by the speaker. And so it acquired a supernatural meaning later.