I have hp laptop with i7 processor.
I am facing a problem as some times my sound services stop working during in video call bt video works perfectly.
I have 3 video calling services
skype.oovoo.logitech vid hd
The best way to fix this is start from scratch.
Remove all software & drivers related to the sound system. Be sure to include all drivers as well since a driver conflict is most likely the reason this is happening. Make sure that after you reboot, you have only the windows drivers being "discovered" and loaded in. After windows has placed the OpSys drivers onto the system, check the devices under system hardware to make sure there are no missing drivers. Then re-install the comm wares you like to use. Add each one individually and check for conflicts with each install. Also your sound panel controls should be set to allow a program to control your sound panel. Something with a description like "allow exclusive control with a program" should be enabled as well.
The main thing - is to have a basic windows sound panel working and functioning correctly before you layer more sound tools on top of it. This assures the proper system hooks are in place for the other tools to find & use correctly also.