In the St22 for your dump, in the left navigation, under ABAP developer view, double click on both "List of ABAP programs affected" (an ascending list of the call stack that led to the offending program), and also double click on "Active Calls / Events".
These may help you resolve how the user got there. Who is the user that caused the dump? If it is not a batch-id, maybe ask them what the heck they were doing.
