So I'm having a problem, and xbox.com and google isn't really helping me and I thought I'd see if you duders could. I have a Halo Reach 360 S that has been running perfectly since purchase. Now all of a sudden when I turn it on, it freezes on the swirly xbox logo screen. I can't get to the dash, I can't bring up the menu, none of the four green lights around the power button light up, and the green lights on the controller just blink. Is it dead? Please help. Any help is greatly appreciated.

Having the exact same problem right now. Although mine only comes into play when interacting with Xbox Live.  It's reaallyy annoying!
 
All I can say is try playing without the Hard Drive. Also try playing without your 360 connected to Live. 
 
See if that changes anything.