Rep Power: 639

Hi guys,i bought this unit DEH-P860MP(used) a week ago and installed it myself.Unit got the power / AM-FM tuner is running good but i am having trouble with compact disc function.i burned and played like 5 different cd's (no scratches at all on cd) but i am getting ERROR-11 AND ERROR-17 in mid of tracks.tracks starts fine but it stops all of a sudden.in manual it says ERROR 11 AND 17 is cuz of scratched cd and may be electrical or mechanical issue.i payed $200 for this unit and even forgot to pick up the remote from guy.Tried calling him few times but no reply from him.i guess i got jacked on this.If anyone can help me with this i would really appreciate that,
Thanks