Dvd playback buzzing or horn sound

[paul1342a]

when I playback movies that I have burned on dvd from downloads on the internet (p2p) I am getting a sound during playback that i can only describe as a loud buzzing or a horn sound. During the playback this will occur from 1 up to about 4 times and the duration will be from apprx 10 seconds to a minute. Only about half of my dvd burns are doing this. I am using a hp dvd 740 light scribe for burning and nero 6.0 that came with the unit. I suspect a copyright protection problem or perhaps a codec problem. Other than this problem the video and audio quality are fine. Does anyone out there have a solution for this. For sure I'm a newbie and this is beyond me. help please.thanks.