It sounds like you have a 1394 connection problem either the cable side or the machine side.
As gtfour45 says try the cables and make sure they are not loose. Swap them around or wiggle them while the system is playing to see if it makes the DCS search for the input. Then you will know it is a connection issue.
As gtfour45 says try the cables and make sure they are not loose. Swap them around or wiggle them while the system is playing to see if it makes the DCS search for the input. Then you will know it is a connection issue.