Version:           unspecified (using KDE 4.6.2) 
OS:                Linux

KDM resets few system settings to default values after using it. I am not sure that you can reproduce this bug if you haven't changed this settings on your system: Fonts and Main Toolbar text.

Fonts:
1. Go to System Settings/Application Appearance/Fonts
2. Click on Adjust All Fonts.
3. Default Fonts on my system are Ubuntu fonts (Kubuntu 11.04 b2). Change it to something else, for example DejaVu Sans.
4. Go to KDM (System Settings/Login Screen/Theme) and change something (install new theme).
5. After that Fonts are again Ubuntu fonts (default value) and not DejaVu Sans as expected.

Main Toolbar text:
1. Default settings

http://img860.imageshack.us/i/mainttoolbarsettingsdef.jpg/

2. My settings

http://img40.imageshack.us/i/mainttoolbarsettingsmys.jpg/

3. After KDM

http://img35.imageshack.us/i/mainttoolbarsettingsset.jpg/


So as you can see "Main toolbar text" has changed from "No text" to "Text beside icons", and all this happens when you use KDM which has another bug (when you install new theme, new theme doesn't appear on list).

Reproducible: Didn't try