gdm error

Hi all,

I'm using debian testing under my old school dell c600.
Since I upgraded today with a apt-get upgrade and apt-get dist-upgrade the Xserver has changed to xorg.

Now GDM always displays the error message:
---
Configuration is not correct
The configuration file contains an invalid command line for the login dialog, so running the default command. Please fix your configuration.
---

GDM version is 2.8.0.6

Then I click on "OK" button and everything works fine.

I don't exactly which file could be causing this error ??

I didn't find any help on google even with the keywords gdm "Configuration is not correct"

Does anybody already knows this problem? Is there a fix or workaround to avoid this error?

Thanks in advance

Nicolas