I've never had this problem before, but I can't insert a ceiling grid from the tool pallette, or light fixtures from the content browser. When I insert either one, I go through all the prompts, but there isn't anything there. It creates the layer, though. I'm stumped. I tried them both in a blank acad template, and the ceiling grid worked, but the lights didn't. After that, I inserted some receptacles from the content browser and they worked fine. Any ideas?