Although ECMerge has an automated test suite which tries to cover most features, and despite all our efforts to avoid crashes. Crashes happen.
Since 2.3.120, ECMerge embeds a crash reporting feature which generates a ZIP file on your Desktop when a crash occurs. You can then send us that file by email at info@elliecomputing.com, if you were comparing documents we might need them to understand the problem (it depends on the complexity of the bug).
We generally reply within a few minutes when such event happens and surely within the next business day.