Problems with console video

[Markus Tarköy]

Hi everybody,
I looked through the archives to find if this question has already been
adressed but I did not find a real answer to my problem. This is what
happens:

         1. Boot into Linux via BootX (Oldworld machine), no video driver
checked --> my console looks allright
         2. startx --> KDE starts up, all looks allright
         3. logout from KDE and now just black screen on all virtual
terminals (I can still type and halt the machine)

Hardware: beige G3 (+Sonnet G4 upgrade 400 MHz), 352 MB, ATI Radeon 7000
Mac Edition, Miro Display 1770

Any hints and suggestions to improve this situation are highly welcome :)
Regards Markus