Reasons why computer problems seem to mysteriously vanish as soon as a technician shows up:
You were spacing out and skipping a step somewhere without realising it, and you can’t reproduce it when you try to demonstrate it because now you’re paying attention to what you’re doing
It’s an intermittent electrical connection fault that’s being aggravated by movement/vibrations in your desk; you need to check your cables
The act of explaining the problem to someone caused you to figure out what you were doing wrong
The real cause of the problem was somewhere upstream of your terminal device – for example, at the network service provider – and it got fixed at the source while you were waiting
Your computer is in a location with poor airflow and is overheating; waiting for the technician to arrive gave it a chance to cool off
Despite all appearances to the contrary, modern computers actually have very good fault recovery, and most minor problems will sort themselves out on their own if you give it a minute
Magic
the computer doesn’t respect you. next time, try firm eye contact to establish dominance.
