Two of my "favourite" jobs to remember in my time as desktop support came from one such user...
The first instance was when he logged a call simply stating "My virtual machine isn't working".
None of our users have a virtual machine to use, so we were pretty confused as to what he was talking about. When I called him up, he insisted that he had a virtual machine. They keyboard & mouse weren't responding and he'd tried repeatedly reconnecting the cables. Remember, virtual, right?
I decided I'd go up to the user's desk to work out what he was actually doing. This "virtual machine" was in fact his laptop's docking station... and he hadn't turned it on.
Fast forward about 6 months, the same user has the same problems again... This time at least, he remembers its called a docking station, but he still struggles with some simple concepts. He told me that the laptop does not work at all when on the dock. No response from the keyboard & mouse plugged in. I asked him if he could take the laptop off the dock and try the built-in keyboard. He couldn't do this because the laptop was locked to the dock for security and he'd forgotten to bring the key with him that day. Oh dear.
I spent a good 15 minutes trawling through the spare keys for user's laptops (Our company is too cheap to buy decent locks so we end up with hundreds of random keys) and can't find his key, but find about 10 unlabelled keys that match the style of his dock. I head up to his desk and I very nearly just threw the keys at him and walked out after what I saw.
He tried to show me the fault by hitting random buttons on the keyboard to prove that it wasn't working. What caught me though was the fact that despite his claim that he couldn't take the laptop off the dock because it was locked, the laptop was in fact, not on the dock. The key that he had left at home was also sitting in the lock barrell. The keyboard was plugged into the dock, not the laptop.
Picked up the laptop, put it on the dock and walked off.
Somehow, this guy still works here and is now responsible for one of our biggest multi-million pound clients.