I've been in more or less the same situation, but for longer periods of time.

I'm curious given your experience. My biggest issue is that I don't know what a 'hard problem' is, I know what comes naturally to me, and what takes me some time to grok, but my experience is that those problems that come natural to me seem to be extremely obtuse to others.

So what types of problems do you solve that allow you to market yourself in such a manor?

I assume you have NDA type structures in place so I expect very general responses.