unexpected view of walls

[Gross]

Attached what happens to me by joining the two perpendicular walls, both associated in height to the roof above. identical behaviour also to walls dissociated in height. a dx identical walls: the problem is not manifested. does not solve or mirror the dx wall or create a new one.
Does anyone have an idea about it?

 

[Tristan]

You don't understand much... did you try to change the joints?

 

[Gross]

the problem seems tied to the window.
cutting the display under the window everything back normal.
I deleted wall and windows reinserting everything from head and now it works (!)