Front surround processing on receiver cutting out

[jtvang125]

Can't remember the exact model but it's a old JVC 5.1 connected to my htpc through an optical connection. Lately the front surround processing keeps cutting out. By front surround processing I mean the vocals from the center and surround sound shifting to the front left and right. This happens only on DTS and DD streams. If I set the receiver to all stereo the sound does not cut out. Also when it does cut out on DTS and DD streams, if I tap the receiver the sound comes back in. All wire connections are good and it still happened when I switched over to a coaxial connection.