Open Win TV and try adding a channel and see if the video and audio play.
The main causes for black screen are "Decoder Issues", no sound card installed in the system, and video cards that do not support "Overlay".
The following information is ONLY a workaround for video cards that do not support Overlay.
If a different Win TV device was previously installed on the system, it is recommended to run the HCWCLEAR utility first before installing the Win TV-PVR-250/350.
This will ensure that all left over files from the older model are no longer on the system.
Open the Primary applet located in the Start - Programs - Hauppauge Win TV program group.