I should keep a more exact count. It seems to me that about half the time the in-seat power doesn't work, including the IAD-PDX flight that I'm on now, a 737-800 with the upgraded console between the first-class seats. The little green light glows but the outlet produces no power for my computer. I'd encountered this on some UA flights with the converter for my phone charger - something in UA's system doesn't like the AC-to-USB gadget - but I've been finding it often with the computer brick as well. Does that mesh with or run counter to your experience with the power supply?