In the import window what is the Destination set to? Check that location for proper permissions. Make sure your Username has read+write permissions.
This error message "files could not be read" is usually caused when you are trying to import raw files and "copy" them to a folder/drive for which you do not have the necessary read and write permissions in your operating system.
Check the Import dialog in the right side panel under Destination and see where the files are being copied to, make sure you have read and write permissions for the folder or select an alternative location to copy the files to. You have to correct the permissions using your operating system.
If you do a search you will find lots of threads in the forum on this issue.