That's a strange problem... It's never happened to me before. Maybe the AUTOCAM OFF command will fix the problem?
Yeah I'm probably way off. Anyway, does this code I've posted keep the screen black? Yes, I know it's kinda random but I wanted to make a bunch of stuff happening to see if it triggered your backdrop issue:
Sync On
Sync Rate 60
Color Backdrop 0
Autocam Off
Randomize Timer()
for c = 1 to 10
obj=rnd(3)
if obj=0
Make Object Cone c,10
endif
if obj=1
Make Object Cube c,10
endif
if obj=2
Make Object Sphere c,10
endif
if obj=3
Make Object Plain c,10,10
endif
position object c,0,0,c*20
yrotate object c,rnd(360)
color object c,rgb( rnd(255) , rnd(255) , rnd(255) )
next c
Position Camera 0,100,-100
do
for c = 1 to 10
turn object left c,1
move object c,1
next c
point camera 0,0,100
move camera left 2
sync
loop