I have the exact same problem. Contacted Xbox Support and they told me to "try a flash drive and see if that works." I highly doubt it will since I have around 3.2GB available on my 360 and I doubt that ODST needs more than that for caching data. Reach will probably be the same. Damn, I'm so pissed right now! I don't even need 250gb! ARGH! This is so retarded!!!