My 42 in hisense plasma will say no signal when i try to use any of the 2 hd sources on it???????????????????????????????

Make sure you set the Source to output at 720p or 576p to start with, once you have the signal on the screen, then change the output source to find the modes your TV supports.

A further note, HDMI uses a protocol call HDCP for copy protection, if you are using a HDCP enable device, your TV will not get a signal as the TV will not have given the correct HDCP code to the device.

So, if all else fails after the above, and you are using a HDMI - DVI connector, try a different source unit.