Im real sorry to bring up such an old thread, but I had the same problem with an HP notebook from 2006.
I just got a new dell inspiron for christmas... guess what, it does it too!
I think some of you are on the wrong track, I can almost guaruntee I know the problem. Its compression IMO. Both of these very different notebooks freeze up when any heavily compressed sound is played loud. For instance, a youtube video that is very LOUD at a low volume setting and distorts easy, same with a .wmv file or .mp3.
Older mp3's can usually be played with all volume settings maxed out, since older CDs have little compression. For example, I am listening to an anita baker song right now, all settings maxed out. Then I will switch to a song off of metallicas latest CD, known to have HEAVY compression to achieve a "loud" sound. Heavy passages causes the hard drive indicator to stay lit constantly, and the computer runs choppy. Backing off the volume fixes it. Some of these youtube videos made with bad cameras and compression that causes massive distortion make it lock up totally.
My dell doesnt do it nearly as bad, since its 5-6 years newer, but still. This probably wouldnt happen with decent external speakers, keeping volume controls mid-level and adjusting the external speakers.