When you use the launcher, It brings up a small splash. When you click to play, it moves the data files from the IS folder to the main data folder. When you are finished playing, you have to close the IS splash in order for the files to go back to the IS folder. When you don't do that, it screws up the whole thing. Make sure to check to see if all of the files returned to the IS folder. If they are not there, they should still be in the main data folder. Move them back in the IS folder and run the launcher. It should run fine.