Hi,
I got a problem with Sound in Windows 7 Operating System (hp pavilion g6 model)..Device drivers are installed properly ..!! I need to restart my laptop every time & sometimes its takes time to restart and many times restart problem occurs..if i restart the laptop, sound is working fine..!!..I have no idea why its not coming sound when i first switch on laptop.!every time i need to restart laptop for sound.! when I update my driver & then no problem in sound but after some day sound problem again start.
Go for BIOS update. check BIOS update on your device's manufacturer website.
I have windows 10 with the same problem, so it is not just windows 7 or 8. I have a Dell XPS 8900 and the Dell Site has no help for this.
I might call Dell and if they have a solution I'll post it.