I was just starting my upgrade when I saw your error screenshot ... and when I went back to my server there it was staring right at my face... !
I had services and task manager MMCs open - I closed them all like Bill says but the screen does not change. I then waited a few minutes, clicked cancel and begin the installation again. It went smoothly from then. am sure you have managed to get it going as well.
The next fun step was recovering the database super user password .. hopefully you remember yours