My DS is 6 months old and he has started doing the babbling and playing when I put him down for his nap. Doesn't worry me too much because it's still quiet time to me. He's in his cot, just talking to himself and then eventually he will fall asleep. If I put his dummy in and he turns his head to one side I know that he will fall asleep straight away. If I put his dummy in and he just looks at me I know he's going to play for a while when I leave. A little while later I'll go in and his head will be to one side and then next minute asleep. All good.

I hope you get things sorted out soon.