The shell appears when opening KDE or Gnome

[Célio Cidral Junior <ccidral.newsbox@gmail.com>]

Hi,

I'm new to Linux and have very little experience with it. I hope
somebody may help me with a problem.

My machine runs Debian Sarge. I'm having a problem with both KDE and
Gnome. When I start a normal session of KDE or Gnome, a shell window
appears instead of the desktop itself. If I type 'exit', it comes back
to the log on screen. If I log on Gnome in security mode, the desktop
appears right and everything works fine.

Does anyone knows how can I fix it?

Thanks!

Célio Cidral Junior