Unlock All Objects

I can't find any mention of this problem on the web or this forum so I am at wits end.  I have a drawing (created in X4 but editing presently in X5) and I can't unlock all objects.  Somehow all objects became locked and I can only unlock them individually which will take hours...I need to unlock all objects but this option is greyed out.

Any idea why the 'unlock all objects' menu option would be greyed out?