you've download openkm from our website openkm.com or sourceforge.net ?
When you start openkm is update a log file called catalina.log into $TOMCAT/log folder. Can you take a look if in the log file appears some error ?
For what I undestand you see login screenshot but you're not able tyo log into, is it ?
Did you make any change from default installation ( change database to use MySQL I recommend on production ) ?