Windows 7 volume mixer resets

Dell Precision M6300 [64 bit]; Win 7 Ultimate
Have tried the following:
Set Control Panel > Hdw & Sound > Sound > Communications > Do Nothing
Installed Windows Codec 4.1.0 4.1.0
Ran System Restore

This problem started a few days ago after a Windows update. Then the System Restore was run to prior the Win update. Volume Mixer Resets to 0; will not allow any adjustment.

Often, if not in focus cannot bring OverDrive Media back into focus directly [1st need to minimize other applications or close it with Win Task Manager].


Happens when running OverDrive Media & Office 2010 & Chrome

Also happens when only running Chrome

Runs OK for several minutes after restarting Windows

First, unless you need that Codec pack for some reason, I might suggest starting there by uninstalling it.
Second, it's possible that somehow during the update process your audio driver has either been corrupted or replace by a less than optimal substitute.
Try going here http://www.dell.com/support/home/us/en/19/product-support/product/precision-m6300/drivers
You'll need to choose the Vista 64 bit drivers as that is the closest match available from Dell it appears. Try reinstalling that and see if it helps.