First of all, look at out Bug-tracking system
http://www.sos-berlin.com/jira/secure/Dashboard.jspa
it could be, that you issue is already reported and solved in the next upcomming version.
In any case, we need the infos about the version of JS, which is used and on which operating-system.
If you can send following files it can speed up the answer to your request:
* scheduler-log-file, * job-/task-log-file, * job-/job-chain-definition (xml files)
This files can be send as an archive to info or support at sos-berlin dot com.