Help... Multiple Audio out of sync

I’ve created an audio mixer that plays back 9 MP3 at the same time. This WAS working perfectly for me, but a few days ago I got a computer virus and since reinstalling everything, it’s not sync-ing up like it used to. It seems like the 1st 5 MP3 are synced together and the last 4 are synced together, but the last 4 play slightly later than the 1st 5. Here is the code I used to assign each MP3 to its own clip.

totalTracks=9;
for (i=1; i<totalTracks+1; i++) {
newSoundHolder=_root.createEmptyMovieClip(‘holder’+i,i)
_root[‘mySound’+i] = new Sound(newSoundHolder);
_root[‘mySound’+i].attachSound(‘sound’+i);
_root[‘mySound’+i].setVolume(0);
_root[‘mySound’+i].start();
_root[‘slider’+i+’_mc’].mySound=_root[‘mySound’+i]
}

Can anyone tell me why they play off sync now, or what I could add to make them start playing at the same time?