In the case of the "Could not find work queue item" error, the user had used "Wait For All Workflow Components In Model (Merge)" despite the fact that there were several linked models that had Dialog Workflows pending. This created an issue when single branches were completing and reaching this component. Since this component only looks at the current model, it would not see the pending Dialog Workflows inside the models. The process completed prematurely and caused the error to be generated. In this situation, the "Wait For All Workflow Components (Merge)" should be used.
If this problem is being caused by the copy/paste problem, any components that were created with copy/paste should be deleted and a fresh copy of the component needs to be dragged over from the Toolbox.
Altiris Workflow Solution 6.0