While we all have MacBooks in this forum most of us don’t have Lion. There's a Lion Support Community where everybody has Lion. You should also post this question there. https://discussions.apple.com/community/mac_os/mac_os_x_v10.7_lion
I had this problem repeatedly on my 2011 Mac Mini Server - downloads would get stuck at the 'downloading additional components' stage even though the internet connection speeds were consistently good and I was connected by Ethernet.
For me, the problem relates to having extra RAM installed. Following advice I found from a couple of Mac forums, I took out my Crucial 8GB memory and put the default 4GB back in, and I've since been able to reinstall with no problems.
No idea why this should cause the install to hang, but for some reason it does.