very strange sound problem in windows 7

Brand new member but I am looking forward to becoming a regular poster so hello everybody.

Sorry to start my posting life with a question but I have been pulling my hair out and am now almost bald I need help here is what is wrong.

I have built my Dad a new PC all works great but there is one very annoying problem . First the system cpu core i7 2600k. mother board gigabyte ga-h67a-ud3h. 8gb corsair xms3 ram. HD4670 HDMI (Yes I know) HDD ocz vertex 2 60gb sata2. and a 1tb western digital for storage. and windows 7 64 bit OEM. Now the problem after I install windows 7 the audio defaults to HDMI I want to run through optical sp/diff so I change the default device to that play some music and all seems to work. so I click the back button and hear a loud pop from my speakers this is not right there should have been a click play (a system sound) so I investigate and no system sounds will play all I am getting is a loud pop from my speakers as though the speaker initialises but no sound then plays so at this stage all media sounds work ie films music and the internet but no application or system sounds. So I continue looking and notice I have 2 sound sliders in volume control one marked device and one marked application I have not seen this before I now open up media player classic ( I installed klite codec pack 64bit as one of the first things I did after installation) and a third sound slider appears in volume control marked media player classic. I then notice that with media player classic running audio or video even if it is paused all the system sounds work but as soon as I close media player classic all system sounds stop working again. I installed klite codec pack and media player classic and the no sound problem is still there but if I launch windows media player it does not fix the sound issue so I re installed k lite codec pack and once again with media player classic open system sounds will play but with it closed they will not. Sorry to ramble but I wanted to be as clear as possible as the problem is driving me nuts any help or ideas would be much appreciated Thank you in advance.

Welcome to the forum allaballa.

Now to get to the good stuff, have you installed your audio driver that came with the mobo? Next, to get the spdf option to work, you have to go into your bios and manually turn it on, by default it should set itself to realtek audio or Via HD audio...or some variation of that. Have a look in your bios to see what you have. I believe your connection is setup one way and in your bios it's set up another way (default settings).

Thank you for the reply and sugestions. The audio is realtek HD audio I have put all the correct audio drivers on directly from the cd that came with the motherboard. I to thought of looking in the bios but there seems to be no options for audio in bios. My audio does work but as I said system sounds will only play if media player classic is open and playing audio I can pause it and system sounds still work but as soon as I close media player classic I loose system sound audio.

checking out your mobo, it seem fairly new; not dated, so there should be something in your bios for changing your audio setup. Go through your bios again, this time very slowly and go through each item in each section till you find it. Once you find it change the settings to spdf. Then there is the bios update itself, which should be done by a professional. If not done right you end up with a big papper weight. You could also do a system repair by loading you OS disc and click system repair, this will rebuild your system files and not harm any data on your system.