it seems that SPARK-228 did not solve this problem completely, http://www.jivesoftware.org/community/thread.jspa?messageID=113972 is a discussion about it and I may quote Derek (developer) “The code I’‘m using to do that does seem a little flaky. I’'m looking into alternatives for a more consistent function to handle the locking of the workspace. Bare with me while I get this fixed” (17.5.2006)