I have a Macbook Air A1237 that I'm trying to install Lion on, but when it restarts to complete installation, it just hangs on a white screen. I've used a usb stick that I put Lion on, I've downloaded Lion from the app store and installed it that way, but it always does the same thing. I can only install as high as 10.6.8 on the laptop. I've read that it can go as high as 10.7.5 and that's all I'm trying to do here. I have the macbook a1237 1.8 ghz 2gb ram with ann upgraded 120 gb ssd