not recognizing ctrl key

All of a sudden, Daz Studio doesn't respond to pressing the "CTRL' key. If I use CTRL-Z to undo an action...nothing happens. If I use CTRL-L to add studio lights, nothing happens. Obviously I've tried restarting my computer, and checked to see that the key works in other applications. I'm mystified.
Comments
Do other shortcuts work? if you hold down the ctrl keyy while double-clicking a preset do you get a dialogue? I suspect the answer will be no and yes, in which case go to Window>Worksapce>Customise, click the Import button, and in the dialogue box select Actions and then in the fiel browser either select Default Advanced or go to C:\Users\YOU\AppData\Roaming\DAZ 3D\Studio4\user layouts\actions and select the file for your saved layout (if you have one).