I deleted the regristy locked file about a month ago but recently I a getting this message when I try to open ckan.
649 [1] ERROR CKAN.ErrorDialog (null) - CKAN is already running for this instance!
If you're certain this is not the case, then delete:
"c:/program files (x86)/steam/SteamApps/common/Kerbal Space Program/CKAN\registry.locked"