>The class creates a number of internal cursors (with a xl_ prefix) that contains the spreadsheet formatting and data in the default datasession. These cursors are destroyed when the class is destroyed. When a XLSX file is opened, a temporary directory is created in the local user's TEMP directory and then loaded into the cursors; after which, the temporary files and directories are removed. The same occurs when you save a XLSX file - temporary files and directories are created in TEMP directory, the ZIP file is created and renamed to XLSX extension, and then the temporary files and directories are removed.

Do you know why your demo sample program doesn't work the second time then?