I believe that would be a hoax picture.
Because industrial systems like that would be custom programmed from the ground up using Unix.
Because Windows just wouldn't be able to do the things they need to do.

They might even use Linux. There's plenty of Linux programmers in Russia, and it's not restricted by any license agreement.
Besides, Bushehr reactor is strictly a non-military reactor, since it is moderated by light-water. Light-water reactor produces miniscule amount of weapons-grade plutonium. If the Israelis wants to stop plutonium production, they first have to find a heavy-water reactor hidden somewhere in Iran.

As the above persons said, i also belive that a error message would not appear on a screen of that importance. they would have back-ups, back-ups for the back-ups which have back-ups for them. The chances of a complete system error are almost non-existent.