Received an old DELL Latitude C400 Windows XP laptop with not working sound. Quick look into device manager revealed the first problem problem: Crystal WDM Audio Codecs device was listed with exclamation mark and Device Status in Properties was “This device cannot start. (Code 10)“.

First off all tried to update sound drivers to the latest available from DELL website. Initially looked like this has worked – sound was working absolutely fine and no errors in device manager. Unfortunately after a reboot I was back to square one – no sound and the same error in the device manager. Whatever I tried to do with drivers (downgrade, upgrade, completely remove from system) result was always the same – sound was working after reinstalling drivers and was gone after a reboot.

This looked like some sort of hardware or driver conflict. Checked Add Removed Programs and noticed two or three pieces of modem software and drivers. This was a bit suspicious as there was no modem listed in the device manager. Quickly removed all modem software; unfortunately no luck, Crystal WDM Audio Codecs still failed to load after reboot. Then found and physically removed actual modem (it was installed next to the RAM module; had to undo two small captive screws and remove a memory module cover). Started the laptop again and was greeted by familiar Windows XP start-up sound, a few more reboots confirmed that sound problem is fixed.

It seems that issue was caused faulty modem interfering with sound hardware or drivers.