When you want to learn a new language, what frustrates you the most about the learning process?

In my mind there's no such thing as a language or technology that is hard to learn. I believe that it's more that many find it hard to teach the language. I have a lot of students and clients who give positive feedback, but there I have a relationship that may distort the opinions expressed.

So, let me ask: what makes languages and technology easy to learn? What makes them hard to learn? And what drives you crazy?