Recently I’ve had a lot of clients with adobe reader issues particularly with the preview pane in windows explorer. Randomly it will just display an error and say “File not found. It may have been moved, edited or deleted. ERR_FILE_NOT_FOUND”. After a little digging I realised that the problem was really simple. For whatever reason, now if there is a # symbol in the file name, it somehow breaks the file path.
Simply remove the # symbol from the file and the preview will work again for that file.