Solar flares

Years ago I hired a contract surveyor to put some points out for us in Oklahoma. I take the survey data he provided and loaded it on to a hand held gps unit so we can find the points. All of the marks were around 120' off from the coordinates. It was a static shift they were all this way all 300 or so points 120' off. He obviously screwed up his base coordinates somehow.

I called him about it and he said it must have been solar flares as he had seen on the news they were gong to be bad. Needless to say we don't use him anymore.

Your situation with errors of a consistent 120' leads me to believe that the error was a difference in the Datum.