There was a change in the sign in process pushed a little bit ago. See:
I wonder if that has anything to do with it. Can you go to connect.trimble.com and sign in?
What “su file” are you referring to? The installer? If that’s what you are looking for go to sketchup.com/downloads/all to get it. Couldn’t hurt to download the installer and then right click on it, choose Run as administrator and then, if prompted, choose Repair.