uninstall Skype video
My dad's machine started doing this for no apparent reason. Even killing desktop Skype didn't stop the notifications "Skype needs to log in...blah blah" clicking on which *obviously*, being Redmond, leads to an error form.
Noticed that a windows store app (or whatever their decided to call them this week) had installed "Skype Video". I uninstalled that and the notifications stopped.