It's Monday morning. Fernando just sat down at his desk for another hard day at work - programming stuff and answering telephone calls - "have you tried turning it off and on again?"
As he is about to login onto his machine he notices a tiny bit of yellow paper sticking out from underneath the keyboard. He moves the keyboard away to find a sticky note with the following text on it:
51577830494373674D773D3D
He is not quite sure what to make of it, but he thinks that the new intern, Ganna, left it for him. The previous night the two were out on a date. He took her to this fancy restaurant and they seemed to have a really good time together. However when they had almost finished eating, she received a call and after a brief moment she said she had an urgent matter to attend to - promptly leaving without offering any explanation.
This made him think that she didn't actually enjoy the date at all - so he didn't quite bother call her afterwards.
Hints:
#1 (Obvious): Ganna is also a WINDOWS software developer. [Thanks for pointing out guys]