Xbox 360 losing my saves!

I do not know how wide spread this is but I popped in Rock Band 2 the other day and found my Band was not there. I was not too miffed since I only played sparingly but then I put in Earth Defense Force and found that my save (Which I have been working on since the game launched) was gone too. I went to the system tray and both those games had no data. It is 100% impossible that I deleted them manually. Not only would I have screamed NOOOOOOOO!!! If I had accidentally deleted my EDF save, but I had 3 saves just in case I accidentally delete 1.  
 
I haven't checked every game, but I know it hasn't happened to every game. And I am using a 120 GB hard drive. Any one else see this or have a fix?