The following error is displayed when exporting the results of a very large (250,000 rows) search to Excel:
Index outside the bounds of the array
In addition, if the Search is configured to be generated and emailed automatically (Report tab), the report will fail to send and the following is recorded in report history (Right click the Search and select "Report | History":
Index was outside the bounds of the array
Rather than setting "Excel" as the attachment type, use another format such as CSV or PDF.
Waiting for fix in a future release of Change Auditor.