Error in iTunes + VLC + Youtube

Hi !

I bought my macbook pro retina 13" in mid-february this year and I encountered 1 big problem that isn't impacting the system but still is pretty frequent.

Sometimes when I play music on iTunes, the song is like "cutted" as if it was lagging but the system isn't... then there's a silent moment and the song continues to play.

It also happens when I play videos with VLC, the video lags up for a few seconds and then continue and the same thing happens with Youtube videos.

Regarding Youtube I already tried a solution I found on the web which consisted on uninstalling Flash and reinstalling it, but it still haven't corrected this issue.

One other thing that is important to note, is that my Mac already froze 2 times since I have it.

I was wondering if any of you guys could help me out.

Thanks !