Error - "An error occurred during the data decompression.". First time I see this error from hoshizora. If it was the patch, then it would just mean that the installer can't extract the files, but no clue what would cause the game to throw a decompression error. The possible causes could just be corrupted files or you don't have some permissions on your Windows Account. You could try downloading everything again, patches, game, etc. Also make sure that your Windows Account doesn't have any odd letters (é, â, etc.). These suggestions are kind of a long shot, but I guess it's worth a try.