Go to http://www.dell.com
Click on Downloads at the top of the Home Page.Look for the Audio Drivers. Download Audio Driver R99254, unpack it but cancel the installation process. Next click on the Start Menu, then click on Control Panel, click on View small icons at the right top of the page. Click on Device Manager and expand System Devices near the bottom. Find the PCI Device entry with a '?' (question mark). next to it. This will be the Multimedia Audio Controller. Go to the Properties and and choose to udate the driver. Choose to Manually find the driver and do not let Windows search for it. Delete the blue highlighted text and type in the browser box c:\Dell\drivers\R99254WDM
You will see the subfolder WDM, this is your audio driver.
It should detect some new hardware and one of them should be the Sigmatel Audio System.
Dell Latitude D610 Multimedia Audio Controller ( no sound after windows 7 installed)
This article on top is the fix for this <error type> code 28, audio driver missing, device changes not detected, etc.etc.etc.....