PSIcapture fails to connect to a database lookup when the ODBC connection is used, and the DSN Data Source is defined to a Excel 97-2003 spreadsheet. Reported errors are that it worked one day and failed the next.
The common variables appear to be clients running Office 365, so Office 2016 is installed. It is likely a office update is breaking communication to Excel 97-2003 via ODBC DSN. You can resolve by converting/saving the XLS as a XLSX file, and then establishing a new DSN using the Microsoft Excel Driver (*.xls, *.xlsx, *.xlsm, *.xlsb)
If you do not have this Driver in the ODBC list, you can get it by installing the MS Access Runtime 2010 components: https://www.microsoft.com/en-us/download/confirmation.aspx?id=13255