Solid stencil shadows

[Veleran]

Though not so often,i do sometimes get shadows like these in the pic:

And,something else:
As the camera zoom in/out or rotates,the stencil shadows dissapear and reappear again.
This happens even when you have only one light in the level and wont get out of its radius.

But..now that i think of it better,maybe i should nt post about it.
Possibly the shadows came up that way because my computer is old and could nt handle it.
I know others would not get these shadows even if they tried...
I just went to the same place but first hided all other brushes and the shadows were ok this time.

Another one:When i have to much brushes in view,the player collision is bugged so much,that he cant go up stairs without jumping.

[paradoxnj]

It looks like it's drawing the shadow volume.