I work as a kind of helldesk for an university administration. The lady calls that she's having problems with our main page css. When she tries to log in to add news the browser says "the page cannot be found".
As it is no use trying to talk the problem over the phone I walk to her room, and ask her to show me how she produces the problem.
So she enters the university main page, let me change the address to a fake one: www.university.com... Then she deletes the 'university.com' and types in 'administration' then she presses enter on such address (www.administration). No, the page cannot be found, no surprise really.
But when she deleted part of the address I spotted something that could have been the right address. So I deleted that www.administration pointed to that address, and pooh, it worked.
"Oh... now it works", says the lady in greatest surprise. "What was the reason?"
I count to five in my mind, and point my finger to the address.
"Perhaps you can spot the difference between _that_ and what you tried to enter here?"
She could. At least that... Geeeez...