The AC adapter appears to be a decent one with a 12VDC/4.58A output, so I doubt that is the issue. Also, I have just used a new Swann RedAlert-DVR in place of the DVR4-Net, and the video coming through that little unit is fine all the way around. So, either there must be something wrong with the DVR4-Net or else it just does not know how to get along with newer cameras and whatever adjustments they can make based upon ambient lighting. The RedAlert-DVR can only record from one camera at a time even though it can accept up to four, and it can only handle a 2GB SD card. However, it seems to work as it should and it just did a good job of catching me wandering around in my carport! Right now I have the camera pointed out at the street, but the picture is too small and the distance too great to be certain as to which of my neighbors just drove past.
If either of you want to play around with the DVR4-Net to see about possibly getting some good video to come out of it, just let me know and I will gladly send it to you. I only paid $35.00 for it, but I still hate to just throw it away.