So I was the network admin for a mining company, and we had just opened another office about 45 minutes drive from the office I normally worked in.  The second day the new office was open I got a call;

“The printers aren’t working.”

Me: “Have you checked all the cables?”

“Yes, everything is hooked up.  We checked twice.”

I run user through the printer checklist.

“It’s still not working, I think you’ll have to come down and fix it”

…45 minutes later

Me: “Well, here’s your problem, the power cable was on the shelf.”