I have HP Pavilion dv7 4160em, with Windows 7, for over a 8 mounts and I have this problem from the beginning and I cant fix it.... sometimes-(randomly) when I look video on you tube or elsewhere, my screen go black but sound remains (repeating sound), like the last sound before go "off" (the screen go black,light on the keyboard go off) but clicking sound from song/video remains and I must hard reset the laptop,nothing else works! I try: update/reinstalling the driver for sound (ATI High Definition CODEC+ATI High Definition Audio Device), and graphic driver-(ATI Mobility Radeon HD 5470), I try to disable ATI High Definition Audio Device ..... I spend over 2h on the phone with technical support but we didn't fix anything I try with different browsers, reinstalling them... I got only kernel power 41,error nothing else... Maybe it got something to do with sound volume and power...??? Sorry fore spelling my English is not good ;)... any idea???