Slack 13 KDE display problem

Hello to you all,

I installed Slackware 13 in vmware on a Windows box first and after
starting the KDE the screen whas all messy. OK, this is a virtual
machine, so maybe it will work when I do a full install on my laptop.

The first time I started KDE on the laptop everything is ok. But that
whas only the first time. Without changing anything the display is
again messed up everytime I start KDE.
It looks like the video card is broken but Windows is still fine. The
background swirls any window swirls ....
The first thing you see when you start it, is a hard disk in silver
but with my version the silver contains white and yellow and the image
has strange curved lines at the top and bottom.

Have deleted all x-windows and kde files from the user folder but that
didn't change anything.

What is going here?? Anybody.

tia.