well if the driver they have doesn't solve it then no other one is going to be able to. sorry to say this but if reinstalling the driver doesn't fix it then it is a hardware problem with the soundchip in the laptop
The driver you need is a Realtek BETA driver. It is commonly available on the Internet
The filename is:-
5898_pg281_win7_turnoff_pullmode_upd
I got mine from '4 Shared'. Had same problem and works fine now. This problem was solved between Microsoft and Realtek. The answer was on a Microsoft Forum.