I tried blocking the pop-ups (Safari has it on their pull-down menu). It didn’t affect anything. Tried activating pop-ups again, but either way had no affect on the linking tool. It still turns the screen dark and freezes.
Never had this happen before upgrading to WordPress 2.7, but right now I don’t remember if it started happening as soon as I made the upgrade. I’m tempted to reinstall 2.7 again, but is this possible without losing everything? Plus I don’t know whether it will resolve anything.
I guess it’s the visual editor, the link button is on the toolbar when you’re writing post, which becomes operable when you highlight the word or phrase you want to link. As soon as I try to use the link button, the whole screen turns dim, like a darkened window shade, and everything freezes.