The error indicates one of the XML files is corrupted.
assuming the report xml is corrupt (example: 75036216, in DCS.NET\DATA with todays date)...
Ask the user how many records were added since pre-test.
Close DCS. Rename the XML file. Restart DCS
Download the report. Explain it may say transmitted, but they will still need to transmit at the end of the day with failed or no response reason.
Explain to the user he will need to re-enter the missing records, if any.