The file cannot be accessed by the system

Bowlsys said:

files were copied from the D drive (HDD) to one of the NAS devices each night. The ISOs were written to the HDD as part of a rar file extraction.

L attribute is marking Reparse points

Since you have backup (image), you could try this:

1. Open Windows Explorer and right click the drive letter where the files are stored that cannot be backed up. Click Properties.

2. From the General tab click "Disk Cleanup".

3. On the Disk Cleanup window, switch to the More Options tab.

4. In the System Restore and Shadow Copies section, click "Clean up..."

5. Click Delete

Your files have APL attributes, P and L are not usual for everyday use. One is indicating symbolic links and other compressed backup (google for detailes)... I'm not on computer atm, so just dhort answer.
Please, do post back about how it went