For years in various KDE versions and on different Linux systems (Mandriva, Fedora) I face the problem:

If a second monitor is connected at my notebook after boot (kdm_greet process) I have to press the backspace key seven times in the password field at the login to be able to type in the password correctly.

Without a second monitor I do not encounter the phenomenon.

In reality it isn't a problem because I got used to it. But it isn't neat.

Installed at the moment: kdm-4.6.2-2.fc14.i686