Playing video issue

Hello there!

In the past few months, when I'm trying playing video on my computer, Inspiron 1545 (purchased June 2010), every few seconds\minutes the video stops for +-0.5 sec and the sound stretched\glitched as well.

When the session's error over, video & sound are back to normal.

It doesn't happen with music!

I tried uninstalling and installing again drivers, remove codecs, install codecs, flash player, etc.

None worked! The problem keep showing!

How can I fix it?

I don't want to format again and again and again and again.

Thanks!