chunks don't load correctly

(I don't found an issue to my bug, if there is one, please can you send me to it)

My map isn't broken, I'm sure.

But when I go somewhere in my world, the chunks don't load and if I want them to load, I must to quit my world and re-launch it. it's worse when we are two in my world. and when I go ''in'' the chunks, an ''invisible wall'' stop me.

I put 1.4.0.5 but it's this since the last update before.

(I do some video but they are too heighty to put them here, so I try to cut one of them to show you exactly)