I just reinstalled the plugin on both my development and test sites without problem. I also looked at the source, and it looks fine.
Did you check to see that the /includes/mstw-utility-functions.php file is in fact there? It should be, but I guess something could have happened with the install.
I also made a change to the plugin’s main file – mstw-csv-exporter.php – and uploaded it to the development trunk. You can download it from the plugin’s developers page. https://wordpress.org/plugins/mstw-csv-exporter/developers/. That’s the only file that changed, so it’s the only file you need to re-load on your site.
Let me know.
-Mark