System menu 4.1 doesn't run on IOS 36, it runs on IOS 60. First, make sure you have cIOS249 installed (rev17) and that you have the latest stable version of USB Loader GX. Make sure USB Loader GX uses IOS249 in the options menu. Try loading a game. If it doesn't work, it is quite probable that your disk got corrupted whilst placing red steel 2 on it. Anyway, to make sure, try using another drive (or just a USB stick) and try loading a game with it. If that works, than the disk is corrupt.