Comment 5 for bug 300028

Thanks man! That did the trick!

As for the file, it supposedly has an attempt not to lock up the login routine:

# The "|| true" is to ensure that the Xsession script does not terminate on error
/usr/bin/xmodmap /usr/share/apps/kxkb/ubuntu.xmodmap || true

Apparently, this doesn't work too well... I guess this is the real bug in this matter.