1.  Alnet Software set to PAL instead of NTSC
2.  PC's Video Card Drivers not installed (Using Default Windows Drivers)
3.  Using Onboard Style Video Card - Need to set to software rendering - (See below).
4.  Cameras not getting correct power
5.  Video Cable connection problems

Here are a few tips:
1.  Click the "NTSC" Button so that it is highlighted in "Camera Settings" --> "Board Tab" --> then Save the Configuration and restart the software.
2.  Load the latest Video card drivers from your Display Adapter Manufacturer's Website
3.  Put Alnet into Software rendering mode by shutting off the "DirectX" Button in "Program Settings" --> "Display" Tab - Save Configuration
4.  Ensure that the correct polarity and voltage is getting to your cameras.  Cup your hands over an infrared camera to see if the LEDs glow (a good sign the camera is getting power)
5.  Move video cables >2-4 feet away from high-load electrical devices, check for loose connectors, or plug the camera directly into the DVR Card or TV with a short length of cable.

These Solutions fix 99% of the blue screen problems that people run into with the Alnet DVR Cards (Trust us  )

Thank you
Platinum CCTV Support
http://Platinum-CCTV.com