Weird behaviour of KDM

[Dr. Harry Knitter]

I have installed OpenBSD 4.0 on an AMD-64 machine an would like to use KDE 
with KDM for login.

First I tried the folowwing in my rc.local:
<code>
        kdm_flags=""

        if [ "X${kdm_flags}" != X"NO" ]; then
           /usr/local/bin/kdm ${kdm_flags} ;
           echo -n 'kdm '
        fi
</code>

Result: I got the login screen as desired (1280x1024 resolution), however my 
keyboard did not work at all.

After searching this mailing-list4s archive I found another way:
<code>
        kdm_flags=""

        if [ X"${kdm_flags}" != X"NO" ]; then
                echo -n ' kdm'; (sleep 5; /usr/local/bin/kdm ${kdm_flags}) &
        fi
</code>

Result: now my keyboard works, however, sometimes I get the right resolution 
(1280x1024) sometimes only standard vga (600x480).

How can I tweak my system to get a reliable KDM with a resolution of 
1280x1024?

Harry