Well, I've installed latest drivers
for Realtek HD Audio in my laptop, ok, it seems work fine, but I think HD Audio really not work fine... it sounds more poor that before, so i've installed R1.92 drivers (it's the drivers who Acer recommend for my Aspire 6930G laptop) but anything work and this causes problem when I reboot or shut down the OS.
I'm going to install R2.14 drivers. I've read that it works with no problems on Windows 7.
ps: Please excuse my limited English. Corrections are welcome.