On my behalf thanks for the answers. I've done all that has been suggested and now we wait. Yesterday went without problems, but as cpro stated the problem may sometimes stay away a few days. I've noticed that usually the volume only goes down (like 9 times from 10) but sometimes it first goes down and the up and so on.. And my volume slider(s) really moves. If this happens and I go and lift the slider up again it might stay there a few minutes and then it comes down again. Or it might stay there a few days. I haven't been able to find any one situation that could be reproduced so that volume would always do the same. So again, same situation as cpro had. Bill2 posted a link that had some good advices. I actually first had the Realtek Manager installed and I also tried disabling the front jack detection, but that didin't help.
So in my case the "fixes" that didn't help are:
-Disabling Voice recognition,
-Telephone call - Do nothing,
-Disable all enhancements,
-Disable Realtek front jack detection,
-uninstall all third party programs and drivers
-install newest third party drivers
Some mixes of the above might do the trick but there's quite many different choises..