Unusable Squeeze: Can't switch off from X to consoles, neither between

[Pier Paolo <pierpaolo.franco@gmail.com>]

  Fresh installation of squeeze here, machine AMD Athlon II x2, board Asus M4A78LT-M LE with integrated Radeon 3000.

The problem is: 
  1)  startx on openbox
  -  Switching between consoles (CTRL+ALT+Fn) make appear a blank screen,

  -  returning to X works (ALT+F7)
  2)  exit from openbox
  -  X closes, but the screen keep blank (black...), for every console (ALT+Fn doesn't work)!

So what??? Please, a mediacenter/server is unusable without VTs...

This problem arise with standard Xorg installation (xorg-video-ati) and radeon driver, and now with fglrx drivers

  Thank you,
Pier Paolo.