I'm sure this has been addressed but I haven't been on in months...but how are u teaching ur LO that hitting is not ok? We've got a very strong willed child on our hands and she is head strong. Telling her "no" doesn't do anything!
I use the warning/timeout system. If he hits, he gets a warning that if he does it again he'll go to timeout. If he does it again, he goes to his timout PNP for one minute. While I take him there I explain that he's going to timeout because hitting isn't nice. He's gotten to the point where he will stop hitting once I warn him, now. You just have to be consistent. DS is very strong willed, too.
Re: Hitting