I don't know if this is just a quirk of NESticle or just something I'm not seeing...

for some reason every time I do something with the name tables/background, it never appears stably: if I try to draw a multi-tile image, the image scrolls vertically (like an out-of-tune TV reciever); if I don't draw anything to the background but just use the $00 background tile, the BG image flickers. sprites do not do this.

anyone know why this happens, and how to correct it?