Test by switching from the IDT driver to the Windows native audio driver. If the same problem while using the native driver then very probably hardware failure of some sort.
1. Open the Device Manager 2. Expand the "Sound, Video & Game Controllers" section. 3. Right click on "IDT High Definition Audio Codec" and select to uninstall. 4. Put a check mark in the option to delete the driver software, and then ok. 5. Restart the laptop.
When the laptop boots up it will look for the IDT files that were removed in step 4. If none found then it will install the native driver. If an earlier version of an IDT driver had been downloaded then its files could still be in the laptop and Windows would install that version, not the native driver. So after step 5, go back to the Device Manager and check again for an IDT driver. Keep uninstalling & restarting until "IDT High Definition Audio" no longer appears under Sound...Controllers. If you see "High Definition Audio Device" that is the native driver.
To re-install an IDT driver you will have to download one from Dell or Realtek.
Jim Coates -- 15 years on the Dell Laptop Audio boards -- since 2/6/04