I have an NEC AccuSync 120 when I turn it on in the morning the display will be about 1/4" taller on the top and bottom than I have it set. Suddenly the display will zoom in, expand out at the top and bottom, just as it gets most exagarated the CRT goes dark but the green power light stays lit. After 5 or 10 minutes when it is warmed up, I push the power button and it works normally and the image is no longer 1/4" larger at the top and bottom.
What could be causing this?