Cut causes security error message

From the CKEditor Demo page, if I highlight text and use the Cut button, I can cut text with no problem. If, however, no text is highlighted and I hit the Cut button, I get a popup that says "Your browser settings don't permit the editor to automatically execute cutting operations." There's some documentation that says this is a Firefox issue, but this is under IE 7.

I'm having a similar problem with this popup in FCKEditor 2.x on my site, but not when text is not highlighted.