OK, this is strange.
A friend in another state send an email from his iPhone asking if I remember how to connect a Mac (he just got a used G5) to the Internet for the first time. I didn’t, so I started clicking icons. I opened System Preferences and clicked Network. It said ‘loading network’ and then I got a pop-up window that says ‘Your network settings have been changed by another application’. I clicked OK and the window popped up again. When I clicked OK again, it popped up again. And so on. The only way to proceed is to Force quit.
I did try restarting the computer, with the same results. So what’s going on?
EDIT: Oh, my AirPort and a couple of other icons are missing from the toolbar now. I’ll restart to see if they come back.