Error OL 808 Object with runtime '0' not defined

[Robin Sahasranam]

I have developed and tested a workflow template in 4.0B which has two
activities: a background standard task executing sync object method followed by
a foreground task executing a  synch object dialog method. The workflow was
working fine initially. Then I added a new container element to the dialog task
and completed the binding from workflow and saved and generated the workflow.
 
The revised workflow however goes into error after the background step
completes. The error message is OL 808 "Object with runtime number '0' not
defined".  I am not able to figure out what is causing this problem. The
extended check on the workflow shows no problems.
 
Your help in resolving this is much appreciated.
 
Robin Sahasranam
World Bank