Knoppix 3.9 problems with screen resolution

On booting up, Knoppix correctly identifies my Philips 105E monitor and says
"Video adaptor = Vesa VGA"
"Using modes 1024x768, 800x600...etc"

With no cheat codes entered I get a totally scrambled screen, as if the horizontal or vertical syncs are wrongly set.

However, changing these to other (lower) values has no effect.

The only way I can get anything to display is using the cheat code xserver=XF86_SVGA.

But this shows hugely enlarged icons, with the "task bar" occupying the bottom 1/4 of the screen.

I have mucked about with all the other cheat codes, but I cannot get any further than this.