Two things to try.
First go to the device manager (right click on the start menu and choose DEVICE MANAGER) Then go to the SOUND,VIDEO AND GAME CONTROLLERS and open this section by clicking on the > so that it expands this section.
Now double click on the device that has the error and choose REINSTALL/REPAIR. It may prompt you where to look, first try WINDOWS UPDATE and if this works it will automatically download and install. If this doesn't work then choose REINSTALL/REPAIR again only this time choose BROWSE MY COMPUTER FOR DRIVER SOFTWARE. Then choose LET ME PICK FROM THE LIST...
When the list opens, the one that is currently being used will be highlighted but there should be at least one more which will likely be "High Definition Audio Device". Choose that one and click NEXT and ignore the warning message if you get one, stating this could be damaging.. Just go ahead and click YES/NEXT. This should solve the problem. You can also choose to uninstall that driver, restart your computer and windows should reinstall it, but I have found this sometimes just places the same driver back. Reading the Microsoft help here will pretty much tell you that same thing.
Of course if this sounds all too technical, just contact me and I can help you further.. obviously existing clients I will be able to connect and fix this ASAP.
