Sounds like a typically overloaded grid and not checking the loading prior to switching off that 400 kV line.
According to several people, including a former teacher of mine Austria is in for a much bigger potential catastrophy though...
Most of our generating capacity is concentrated in the eastern and northern region (hydro, caloric, lots of wind turbines), whereas the south doesn't have much generation capacity but heavy demand.
Those two areas are linked by two constantly overloaded 220kV lines.
Since they're that heavily loaded it's impossible to shut them down for maintenance. But live maintenance like painting pylons is illegal in Austria, so the pylons can't be painted...
So IF one of those lines fails, it'll most likely shut down at least half of Austria, probably taking down large areas of Europe.