When i checked the device installed, the media audio controller has a yellow exclamation point on it, sometimes PC suddenly stops and need reboot.
but i still can listen song,but i don't know why it stops and need reboot.
i try to reinstall it,but it say "cannot install this hardware".
anyone know why and how to fix it ?

You can try reinstalling the sound card drivers,either from a CD or by downloading

them.The Realtek AC`97 drivers are HERE if that is what you need.

You can also post some minidumps (crash reports) C:\Windows\minidump if your still getting crashes.

i installed Realtek AC`97 drivers and i din't see anything in my crash reports) D:\Windows\minidump