If you specify the OVERLAY= option in any control chart statement in PROC SHEWHART and there are more than 105 subgroups, the procedure might terminate abnormally and issue one of the following messages in the log:

ERROR: Write Access Violation In Task ( SHEWHART ];
ERROR: Unable to open utility file.
ERROR:Read Access Violation In Task ( Graph Window ]

You might receive a pop-up window with the following message:

Element being freed causes memory overlap

To circumvent the problem, either omit the OVERLAY= option or reduce the number of subgroups. Since there is not a specific number of subgroups beyond 105 that causes the problem, it might take some trial and error in reducing down to a number that executes successfully.