Receiving this error could mean that the file association between the PlayOnline Viewer and FINAL FANTASY XI is not working properly. Please try running a full file scan to verify the integrity of your game files. If this does not resolve the issue, please try reinstalling FINAL FANTASY XI to correct the issue. If you still require assistance in resolving this issue, please click on the "This Did Not Answer My Question" button below to contact a SQUARE ENIX Support Centre agent.