Fixed: Adobe InDesign CS5 layers menu grayed-out

I came across an issue on a coworker’s Mac where the Layers toolbox and menu in InDesign CS5 were grayed out and unusable. Several calls to Adobe support bore no fruit, so I started troubleshooting the issue myself. It turns out there was a permissions issue for some folders under /Users/<username>/Library/Application Support/Adobe. After resetting the permissions to grant the user and Administrators full access to all contents, the layers problem still existed. The final fix was to open the Adobe Extensions Manager, locate and un-check the Layers Menu extension under InDesign, restart InDesign, re-check the Layers Menu extension, then restart InDesign one more time. After that, my coworker has been able to use layers in InDesign without issue.