The most frustrating thing:

1. Someone asks for help

2. I help them but not right away

3. Turns out they found a solution and my time spent preparing to help them was wasted

I don't mind the fact I spent time on it because often I learn something or provided a better answer than the person found for themselves (not to mention if it's in my day job I still got paid), but I can't seem to find a polite way to teach people "I'll get to the question but please tell me if you solved the problem yourself"