My new Dell 25" Ultrasharp monitor is great when it works, but when it resumes from sleep it shows the following screen / message.

"Unsupported audio format. Please set the audio output on your audio player to Pulse Code Modulation (PCM) if available."

Usually this screen shows up for a fraction of a second, then it goes dark again. Sometimes I get actual static for 3-5 seconds before it goes dark. This repeats until I hold the power button to turn the computer off. When I turn the computer on again it's working. Once it comes back the OS spends ages checking the disks.

I've read about this on the Dell forum, apparently it's to do with the HDMI port sending sound, even though the monitor has no speaker and nothing is playing. The standard solution is to use Display Port, but my work laptop uses that, so I need to get the HDMI port working. I've gone into Windows sound preferences and deleted the Dell monitor as an output device. With nVidia cards there's an option to disable sound, but my AMD software "Adrenaline edition" doesn't seem to have that feature anywhere I can find.

Does anyone have any suggestions? I'll call Dell support Monday when they open, but I hope Geekzone can solve the problem before then :)