Impossible to change resolution screen

Heya there
I've jsut installed a Knoppix Linux Azur on my HD. But i've a little pb. In the KDE config panel, i cant change the screen resolution, the refresh rate etc.. I can choose all the resolutions (800x600, 1024x768 etc) but when i apply the changes, it does nothing and when i return on the configuration panel, nothing has changed. I can only be on 640x480 refresh rate : 85
My screen is an Acer 54eL, my video card : GeForce2 MX400.
Before installing it on my HD, i tried the livecd. But when it booted, the monitor didnt display anything. It only worked when i put the following boot parameter : xvrefresh=60
Can someone help me ?
Thanks a lot.

There's a cheatcode to set the resolution too. Did you try it also?

JD

When LILO appears, i choose Linux but where to put the cheat code ?
Do the cheat codes work with an install on HD ? I know it works with Livecd but for an install on HD i dunno.

After booting Knx. open a shell and type '/usr/bin/kxconfig' (as root). This to enter Xdisplay where you can set various monitor settings.