I was discussing setting up a laptop to improve security.
Me:"I'll just quickly set up an Admin and a Guest login so you can install programs in Admin and surf the web in Guest."
Other:"Thats no good, it won't work."
Me:"What do you mean?"
Other:"I can't use the web as Guest, I have to be in Admin."
Me:"No, don't browse the net in Admin, use Guest."
Other:"But I can't respond to my forums as Guest, only read them."
Me:"...oh, I see where the problem is."
Diplomatic explanation followed, explaining that it is a common mistake to make (even though it was the first time I had heard it).