I get the same problem as many but slightly different. When I go to boot my 360 slim, it will say I need to download a patch. I tried the first time then it said I was out of memory. I know I have over half my HDD available so that can't be the case. I skip the patch and I load to my dashboard but obviously can't sign into xbox live. I check my HDD and it says "unformated". I turn off the xbox, turn it back on. Same problem. I turn it off, turn it back on, now it loads and works fine. I've been dealing with this for a couple weeks now. If it turn it off and back on a few times my hard drive error goes away. Any ideas here?