I have been experiencing issues with the sound of my T420s after upgrading to Windows 8.
The error I am getting is:
"The current Dolby audio driver version is 7.2.8000.14 and the software application expects driver version 7.2.7000.7. Please install a valid driver and software application combination."
I have uninstalled the Dolby driver and reinstalled the 7.2.7000.7 (checked it on Program and Features) but again the same problem.
Install both these components and now the problem should be resolved
1) Update Conexant Driver to Conexant Audio Software version 220.127.116.11
2) Dolby Home Theatre v4 is listed at version 7.2.8000.17. This update can be found here