I can use Command+W when there are multiple tabs open to close one window at a time, but not when there is only one window remaining. It's driving me crazy because I have to click on the red dot. It won't close with File > Close either. Nothing changed (that I know of) from last week to this that would cause this. It works fine in safe mode but I can't figure out what's conflicting. Also, I've tried reinstalling Firefox but that did nothing. Help?