Blank monitor after switching between virtual consoles

I have recently installed SuSE Linux 7.3 Professional on a system, which now behaves in a manner that I have never seen before: When the system has booted, I can log in through kdm and out again as any user on the system. If I switch to any of the virtual consoles tty1 through tty6 I can log in, but as soon as I log out again, I get a blank monitor. Trying to switch between virtual consoles or back to tty7 where X resides does nothing for me. The power-LED on the monitor is still green. The monitor's power-LED is amber if the monitor lacks signal or is in suspend-mode. The system has APM disabled, so that's not disturbing. What can this be? Best regards, David List