How To Fix a Boot Problem

My friends macbook air won't boot properly it gets up to displaying the Apple symbol and chimes but after 5 minutes it comes up with an Apple logo with a cross over it at first I thought it might be a hard drive problem but then I remembered that OSX 10.7.5 scans for a Apple only security chip and if it doesn't find it OSX will refuse to boot.has anybody else experienced something like this and if you have how did you fix it?