Latest Flash player ruins my Realtek sound

Ever since I have installed the latest version of Flash player (version 11,2,202,233), there is no sound anymore in any Flash movie (eg. YouTube). I do see the movie itself, so the Flash-plugin is functioning.

My ASUS P5K motherboard has on-board Realtek HD Audio sound (full specs at hyperlink). Once I reinstall the audio driver, the sound reappears after the first reboot (even in Flash movies). However, once I've played one (or a few) Flash movies after the initial reboot next to (re-)installing the latest audio drivers, the sound magicially disappears again.

At that point, there's no audio controller visible anymore in the control panel. Volume control (sndvol32.exe) shows a dialog box on execution stating that there is no audio device and then quits. The strange thing is: I do hear the log-on and log-off sounds when switching users in Windows. And I do hear sound using the VLC media player.

I use Windows XP (Dutch) with all the latest updates installed. Everything worked perfectly fine up and until installing the latest version of Flash player. Please advice. I'd rather re-install the previous version of Flash then to continue using this version.