font too small on login connection

[abdelkader belahcene]

Hi,
I use the gdm interface on the sarge debian, on some machine there is no problem, on other the font is too small and I couldn't read it, eene if i change the resolution.  After login everything is correct, I just have a problem in the login interface, I tried different theme. same problem.  I want to know from where it takes the login image ??  (by the way the  image is correct for example I can see on an image displayer correctly /usr/share/gdm/themes/happygnome/screenshot.png).
I am not sure that the problem is gdm, since same problem with kdm.

Thanks for help
bela