System: Dell Dimension 4600, Dell Flat panel monitor 1703FP HAS, operating in analogue format, and ATI Radeon 128MB 64bit video board

Before I downloaded service pack 3, I could operate my monitor in portrait format but now it will only operate in landscape format.

If I go to the ATI symbol in the systems tray -> rotations -> 90 left I get:
'The requested rotation is not supported by your current display mode …etc.

Going to ATI -> Display Properties-> Monitor it seems only to admit a refresh rate of 60 or 70 Hz as alternatives, neither of which makes any difference to the problem.

I have updated drivers for the board with no effect on this problem.

Since I often find portrait format very convenient I would welcome any advice.

Thanks in anticipation, Aging Dog.

P.S. I’ll add my name to the list of confused users of this site. Nearly gave up!