To confirm, you do have the auto-unprotect package installed? Is it just one programme, or all of them in that folder? If the latter try creating a new folder and move the programmes in to it. If it still fails, ensuring that the 'enc' flag has been removed by auto-unprotect, try copying the programmes to an external USB drive using the 'opt+' move/copy option with the remote control. This is another way of decrypting. If this works OK, copy back to the internal hard drive, check that the programmes have the green 'Dec' flag and try and play on the remote machine from the network share.
The above might work but won't tell you what is causing the problem. Someone else may be able to solve the issue by suggesting diagnostics to run.