Opposite (OTP) and Parallel (PTP) are 2 different ways a DVD9 is mastered. In OTP layer 0 starts at middle of the disc and works towards the outside, layer 1 then starts where layer 0 stopped and heads back into the middle of the disc.
PTP again layer 0 starts at the middle and works towards the outside, then layer 1 also starts at the middle and works towards the outside.
At present all DL burners can only burn OTP.
As to why you are having problems ripping OTP discs I have no idea - sorry!!