My blu ray dvd has flashing horizontal white light

Try a different DVD to see if it is the Blu Ray disc. If you still get the line, then put it on VCR, Cable, or Satellite input to see if it is the TV.  If it is the DVD, power down the unit and power back on to see if resolves itself.  If you still see the white line, then the pickup laser lens is defective meaning your player is fu.k.d up.  Take the thing back to the store for refund or exchange if your within your 30 day window and you got the receipt.  Otherwise you got to contact the manufacturer if your within your one year window.  If this thing is too old, then you got to throw it away and wait until Black Friday to score you a good deal on another Blu Ray player.  CNN says retailers are hurting for business this year so don't be surprised to see Blu Ray players retailing for $150-$200.