your desk is very untidy and has paper, reports, books, magazines, stats lying all over it, your brain momentarily picks this up when you are not working. So when you get to working you could be thinking 'I've got that report to finish, I need to finish those stats, I need to show Steve that article in the magazine'.
We still have lots of information to contend with in our minds. Whereas if our desk is completely free from clutter we are much more likely to focus and get the task at hand completed. This is also true at home, tidy house - tidy mind. (taken from dumblittleman.com)