I'm posting this as I'm equally interested in any opinions as well as to post my findings for anyone else finding this with a similar problem scenario. I recently bought an ATI Radeon HD 5450 graphics card. I installed it using its low profile bracket (so i unplugged and removed the VGA port for my system) I first posted when i noticed a problem not hearing most Windows system sounds. I first thought it had something to do with .wav files (which is how system sounds are stored) But after lots of testing, i've concluded (with 99% confidence) the issue isn't the wav file itself but rather how long the sound stream is: i.e. I'm not hearing the first second or so of sound. So i'm not hearing things like beeps and alerts simply because they're "short" sounds (timewise). Also this problem only occurs for playback over HDMI with ATI's addon card. All sounds are heard OK when i select to playback using Soundmax drivers with the onboard audio (in which case, it plays OK over both Dell's internal speakers and through the headphone jacks). And, btw, this problem occurs with both Windows XP Pro and Windows 7 Professional x86. I suppose i'll just try a new sound card next... Anyone ever seen anything similar? Could it be a power problem? Hardware issue? or maybe just a buggy driver??? /* edit */ By the way, to help prove my suspicions i built my own Test.wav file which uses and merges system sounds C:\Windows\media\ding.wav and tata.wav. I've uploaded the file here. If you want to test with it, unzip it and click it to play it. If it plays back correctly, you should hear 4 distinct system sounds: ding->tada->ding->tada.