Sorry, I don't check the forums every day, and I've recently moved house and have had little time.
This error was likely generated because the game is installed to a protected area of the operating system where file operations by applications are restricted. However, I changed Eufloria's file IO permissions such that it should be able to write to this location, so it's possible the file got locked by some other process or by another instance of Eufloria or something.
Try each or all of the following:
1. Check the file access permissions for that file (find it in Explorer and right click the file, go to properties, uncheck read only if it's checked)
2. Unlock the file by running a file unlocker
3. Run the game as administrator (right click the game exe to get the drop down menu, and select run as administrator)
4. Move the game folder to somewhere less secure e.g. your desktop or your documents folder
Let me know by PM if this doesn't help.