Hyundai ImageQuest Q770 - Screen image stretches in use!

Hi, hope someone can help me.

I received the Hyundai Imagequest Q770 17" monitor yesterday and I have noticed something strange.
When I have a non-bright background (desktop or web page) and I then open a window that is bright (like white) it makes the screen stretch (expand) to the left and right. Then when I close the window the screen dimensions move back to normal. It is very noticable.

For instance it happens when I open the Control Panel the screen expands, close it and it reverts to normal.

I have an example 3Mb video if anyone wants to check (its small but the effect can be clearly seen) here. It's noticable more looking at the left side of the screen.

Never happened with my old 17" monitor. Hopefully there are other Hyundai Q770 owners that can shed some light if there is a problem with this particular monitor. I am using the standard VGA connector that came with the monitor.

I have yet to phone Hyundai, it comes with a three year warranty.

All CRTs do that to some extent. The better they can control the power supply volages the more stable the image/screen size will be. A white screen uses more power as all three RGB electron guns are producing electron beams. If the control voltages sag, then the image size control degrades.