Acer Aspire 4736Z
Problem in playing audio and video files

Hi

A month back, i bought a Acer Laptop from Modern Computers Chennai (AshokNagar Branch). I face the following problem,

Video files and audio songs are not playing properly in both dvd mode and hard disk mode (Hard disk mode - copy the entire dvd contents in to local hard disk), I am using VLC player and Window Media player,

If i am playing songs, it give acoustic sound.

If i am playing any video files, it should get stuck and play and produce acoustic sound

I tried this for more than 50 Original DVD's, but still i face the same problem

i contact the acer customer serice, they immediately change mother board, but still i am facing the same problem

could you please help me to solve this issues