Main Camera Stops working or just freezes?

Hey there,

I'm having this strange issue with my main camera. It tends to switch to a different camera or when there's no other camera persent in the scene to freeze and "darken". I have my main camera set as a child of the player object. Then another camera as a child of the main one. (MainCam's culling mask is set to everything while the child cams culling mask is set to one particular layer. I'm using this to prevent the object-going-trough-stuff thing.) The depth of the main cam is 1 and the child cams depth is set to 2.

This happens only when I'm looking in a certain direction. (This screwing-stuff-up direction seems to be different each time I play the game.) Also, when there's no other camera outside the player object and the main camera freezes and gets all dark, the child camera is still working so I can see that one layer it's rendering. It just looks like the clear flags of the main camera are set to 'Don't Clear'. But as soon as I look away from that direction it goes back to normal.

Another thing I've noticed in one of my past projects is that if I were to remove the child camera, this issue'd go away. I don't know if it'll work in this project. If it will and I'll end up having to remove the child camera, how would I go about the things-going-trough-walls-n-stuff ?

Thanks.