Hello, I have exactly the same issue. I've just built a brand-new PC running on Windows 10 and I'm trying to install Paint.net (which worked fine on my old Vista laptop) and it keeps telling me there's another ongoing installation. There are no ongoing windows updates and I'm up to date, and I've restarted the computer half a dozen times. I'm not sure if it's worth me making a separate post for what appears to be the same problem, but I will do that if that's easier for you
EDIT: Oh man, I just created this account and it must have pulled that photo from my email account. That is an old photo