I was helping one of the staff today with their Debian setup. KDE somehow broke after they did an apt-get update. Turns out there must have been like 40-50 packages that must have been in the update and thus one of them broke during the upgrade.
Upon startup, there was a unique error message that came up with KDE during the startup phase — “No greeter widget plugin loaded. Check the configuration.” with an OK box. Clicking the OK box would lead to KDE exiting to shell. Reinstalling kdm had no effect. The fix?
apt-get install kdebase-workspace
Seems like the dependency of kde install/update is missing the kdebase-workspace package.
To check to see if this works, restart KDE by going to
/etc/init.d/kdm stop
/etc/init.d/kdm start