Following the usual advice to "make sure you have the latest drivers installed" I have downloaded Realtek ALC650 AC97 Drivers v A3.64 . It's saved as an exe file, 10.5Mb, as stated on the page, but when I try to run it there's just a flicker of a DOS window, then nothing.
What am I doing wrong?

Open up a dos window, then execute the file again. Any error messages will remain on the screen. You may find the the file is corrupt.

Thanks - tired that, but get a message to the effect that there's not enough memory.

Open & extract it with WinRAR (http://www.rarsoft.com/).

It shows as an exe - not a zip or any other extension.

Oh! Well, that got me a whole lot of new files and stuff. Now I just have to find what to do with it. Thanks for pointing me the right way.

Are you sure you downloaded the drivers for Windows?

Think so - I got the ones which the page said were for XP. The WinRAR let me unzip it all. I'd assumed that as an exe file it would just run like most installers do.

you should be able to right click, press extract here, go to the hardware and devices screen and search for the driver in the location you just extracted to.

Thanks - fingers crossed then.