cyanogenmod - Why can't my phone find pictures or music files suddenly?

I have a Samsung Galaxy Ace with its official CyanogenMod nightly build. And suddenly, it doesn't "see" my pictures, videos or music files. They don't show:

1. while selecting a notification/ring tone & default music player,


2. while viewing pictures in QuickPic or the default gallery, and


3. on Go Launcher Ex's videos and music finder feature.

However, ES File Explorer, the default File Manager, and PowerAmp clearly show the said types of files. I've done a NANDROID backup, wiped the partitions then restored the backup, still no go.

Answer

Ah, cripes. I don't know what on Earth put this .nomedia file on the root of my SD card. Problem fixed.