The ribbon becomes grayed out when the acad.cuix is loaded at the same time than the aca.cuix.

To enable the icons, unload the acad.cuix. Follow these steps:

1. Type MENULOAD at the command line.
2. In the Load/Unload Customizations dialog box, select ACAD in the list.
3. Click Unload.
4. Click Close to close the Load/Unload Customizations dialog box.

If you want to use ribbons, menus from the acad.cuix file, use the Transfer tab from the Customize User Interface (CUI).