same thing just started happening to me after years of using paint.net
i did delete some of the windows snooping updates they snuck in,
maybe that was it
now paint.net refuses to open anymore
what exactly is in sp1 that paint.net needs that photoshop/illustrator/gimp/coreldraw/xara/serif/photofiltre/etc. don't need?
the last thing you should tell people to do is have automatic updates on
big mistake for bloatware/privacy/uselessness