My DVD rom is Pioneer 105(the one that draws discs in instead of using a disc tray),and after one year of using,it doesn't read any dual-layer DVD now(No problem with CDs or single-layer DVDs though).So I opened it up and cleaned its lens using a Q-tip with alcohol,and then it can read dual-layer DVD again.But this brings a new problem:now whenever it's playing a DVD movie,the picture is always shaking and the sound is stuttering(both single and dual layer DVD,but no problem when watching VCD).I tried a number of DVD playing softerwares and the results are same.