So when Lion came out last week, I went ahead and bought and downloaded it… I then spent 3 or 4 days trying to figure out why I couldn’t install it. I was also experiencing some problems with my installation of Snow Leopard and even trying to boot my known good Snow Leopard installer disk. The problems I was experiencing was that when booting up, it would completely freeze once everything came up and would sit like that for 5 minutes or so before I could start using it. Lion would not install stating only “An error has occurred, please run this program again later”
Only after I had been doing some searching for the errors that showed up in the installation log, I found a suggestion to try clearing the PRAM and NVRAM. I did that by turning on my Macbook Pro while holding down Option, Command, P, and R. And guess what, everything worked fine then.
So, my suggestion to any mac owners that are experiencing weird problems, reset your PRAM and NVRAM before you spend days searching for the answer like myself.