BleepingComputer.com: CSS graphics muck up. :(

I posted this on another forum on here but,
I thought i would post it in this one just incase someone
sees it?

I have Windows XP Professional
Counter Strike source,
I run this through Steam.
Heres the problem...
"VGA MODE NOT SUPPORT H:75. OKHz V:74.9Hz"
This appeared on my brothers monitor,
When i changed the resolution/Graphics on
Counter Strike Source.
This only happens when i enter the game,
Everything else seems to be running smoothly.
I am getting sound when playing the game but
no picture? And it is as if the picture has moved below
quite a bit???
Was going to F8 safe mode and change the settings,
Which i think is the right thing to do??
But from previous problems,
Every time the computer starts up.
We have to choose out of XP home edition or XP pro.
So i didnt want to fiddle with them options.
Not being completely computer litterate,
I need some help please...
Thanks.

When you run certain screen resolutions, it also changes your monitors refresh rate. It would appear your monitor doesn't support the resolution/refresh rate you have chosen. Try changing it through the counter strike source game itself.