My Xbox360 received a system update and now whenever i play games i have to update every single time, why?

[Vladmir Dracul]

If i put in Halo: Reach for example, i will need to update and if i take it out and put it back in i will need to update again. I have the new Xbox Slim (came with 250gig hard drive). This doesn't happen with friends Xbox just mine, why is that?