The cIOS installer offers you 2 options, WAD install or Network install. WAD install requires the base IOS WAD files to be on the root of the SD so it can patch them. Network install downloads the IOS WADs and patches on the fly. If you dont have the WADs (required for WAD install), or your wireless setings aren't set up correctly (requred for network install) then the app can code dump (numbers and letters on the screen) can occur