Panasonic NV-GS11 EG playback problems

Hi everyone,
first of all, I apologize for my poor english. I have this camcorder from 1.5 years and I didn't have any problems till' now. I look over the forum, but I didn't see a topic about this, maybe I'm wrong and in this case I want to scuse me...That's my problem: some times, not all the times, if I rewind a recorded tape and I want to play it, the camcorder display a pixeled image or some longitudinal black stripes over the image. No dirty head indicator appears and there are no problems with recording, only with playing...Some times, on play, a complete black image appears with 16bit audio altghough the counter goes on and the recorded tape is on 12bit audio. Is anyone who can give me a help?
Thanks a lot.
Muhi