Files greyed out on external disk

Hi - I have an external USB disk with many folders and files on it mostly pictures. The disk is formatted windows NTFS as it is used on a PC as well. Most files are accessible by mounting using ntfsmounter, but all files in one folder are greyed out and will not open or copy as finder displays a message stating the file is in use by OS X. The files are all OK, and open in quick view, but not any other program. They are obviously locked somehow or is there a permissions issue that can be resolved? I am stumped by this at the moment and would appreciate any assistance.

Did you try to command click (right click) on the folder, select get info, and check its permissions? If the entire folder is read only, click on the small lock at the bottom, enter your admin password, and change permissions to read and write.