Whenever I print from okular, the print succeeds and then I see a dialog from the plasma desktop shell asking "Enter an username and password to complete the task" (sic). The usename supplied is root, and if i give the root password the dialog disappears. If I give my own username (the one i used for printing), the dialog comes back with root as default.

This happens every time I use okular. How do I stop it?

And it seems only to be okular - if i use lpr from konsole, or even the print screen menu in konsile this doesn't happen.