i did dual boot windows xp and BT4 final the problem is after i finsih installing bt4 i realized that no sound in windows xp and i mean like the sound card does not exist while the sound work fine in Bt4 the first time happened i thought there a problem in windows however when i removed Bt4 and restore mbr the sound in windows worked just fine . i really have no idea what the hell is going on since i have never experience such problem with other backtrack at all . any suggestions or thoughts?