Update^2
Posted By Quentin Carnicelli on September 23rd, 2006
Derek K. Miller: “Why, if I want to install Adobe Reader […], should I download a program that runs an installer to install some software to download an updater than downloads more files to run an installer that installs software that is way too big and slow to start…” [via Daring Fireball]
Although Adobe Reader install process proves to be the most painful, second place goes to the Adobe Creative Suite for the following dialog alone. I title it, “Update”:

When I first saw it, I was disappointed that the “OK” button wasn’t labeled “Update”.