DS just turned 3. For the last several weeks, he's been ignoring us - blanking us out if we speak to him, refusing to make eye contact, not responding verbally if we ask him direct questions. It's not all the time, of course, and most obviously, it's usually if we try to talk to him about something he's either not bothered about, or wants to evade. So if he doesn't fancy going to his music group, for example, or sitting down to eat lunch, or if I want him to say what he wants to wear and he's not bothered, I get a big ignore. It drives me mad, though!
He's recently started refusing to say goodbye to much-loved grandparents too, or even hello sometimes. 
He used to make eye contact (he was a little flirt and charmer) with random strangers who spoke to him in the street when he was 2, as well as loved aquaintences like the local librarian, but he doesn't talk to people he doesn't know now, either. He shrinks away and hides his face mostly.
This goes along with a host of other late-2s/3 yr old-isms that I presume are par for the course - temper tantrums, silly voices when he's overtired, getting frustrated with himself, saying 'no' a lot. But the lack of response is really getting to me. I keep on thinking it must be my crappy parenting, that I must just nag on at him so much that he's decided to blank me out. But he does it with other people too.
The obvious things that have happened in the last 5 months are: we moved house. Not far, just to the next village so many of his points of reference - shops, park, friends, etc - are the same, but he really misses his old house and village and when he gets tired/ill/upset, he cries and says he wants to go back to Home Village. What can you do?
The other thing is that I had another baby boy a couple of months ago. He was very excited and is very affectionate to his brother, and loves him. But I'm not daft - I'm sure a lot of the problems we're having with DS1 at the moment stem from his new baby brother, however indirectly he expresses them.
Please tell me he's normal and will grow out of this! At the moment, I'm finding it really hard to make contact. He'll consent to having a story read (when I can manage it around DS2) but I think being tied to the new baby is putting a large wedge between us. Maybe this blanking is a way of punishing me for that? At the very least, the ignoring thing is driving DH and me round the bend - we can't get him to verbally consent, agree, affirm anything at the moment. So we do it anyway and feel like we're bulldozing him. And I miss the nice simple way we used to be with him.
(DH is convinced I'm worrying about nothing, incidentally, and he's a psychologist (not clinical). But...)