Hey all - can someone one please help me

I have a DCS-932L camera setup in my living room with motion detection activated in DView. During the day it works great, but after nightfall the camera shows random lines in the [poor] video. These lines are being picked up as motion and as such the camera records all night long taking up massive amounts of disk space. Even when I put the camera motion detection on 'lowest' value, it still picks it up.
Is there any way to resolve this issue? Thank you!!