13.37 as guest in virtualbox 4.1
 

Finally getting around to setting my virtauls up again, downloaded the latest virtualbox 4.1 and slackware can't startx, anyone seen that before, searches bring up a lot of other versions.

Which do you suspect the VM or the slackware?

What is the host OS?

What is the /var log errors or xorg errors reported?

I'd assume you should be able to at least run it in vesa mode.

You have to reinstall the Guest Additions after upgrading VirtualBox.

Slackware 13.37 is also the host. This is a fresh new install of the guest, I never had to do anything before, the video just worked so it caught me by surprise.

edit ~/.kde/share/config/kwinrc and change OpenGLIsUnsafe=false to OpenGLIsUnsafe=true

You need to reinstall the guest additions to obtain full screen video, but you should be able to start X at 800x600 without the guest additions. You might need the same solution I found.

That was it, OpenGL

This was a new install, installed additions the first time. X wouldn't start no matter what resolution and full screen or not.