Hello,
This appears to be a problem with the ACL (access control list) which is preventing FlashFXP from saving the data files.
The easiest solution is to re-install FlashFXP and typically this will solve this problem.
https://oss.azurewebsites.net/download.php
Another solution is to download this special application we've created, it will attempt to fix the problem provided FlashFXP was previously installed successfully.
http://download.flashfxp.com/FlashFXPSetPerm.zip
You can find your data folder from within FlashFXP, navigate the main menu > Help > About, and click on the details tab.