An error occurred while preparing the installation. Try running this application again.

The system places the Lion installer automatically in the applications folder after the download was completed.

Fair enough, I'm attempting to burn it to DVD and install from there now. I'd also like to add that it was installed to my /applications folder. So thats not helping either.

I've tried installing it from the applications folder and it still doesnt work.

upgrading to snow leopard 10.6.8, which came out today worked for me! good luck guys!

I upgraded to 10.6.8, and it's still not working. Ugh. If any of you figure out a work around please let us know.

Thanks that worked for me and also fixed the mouse startup problem..

After four hours of troubleshooting, this solution ended up being the one that worked! Thanks!

Please confirm key sequence? Is that P and & ?

Zapping the PRAM worked for me as well.

This (copy to Applications folder, and then run it) worked for me on Mac Air (original release version). Lion simply did not like installing from external DVDROM at all.

Thank you, Mr. Marron.

This what worked for me. Many thanks 🙂

Wow, after 6 hours, rebooting, repairing, reloading - checking the date in the Terminal and correcting it, finally resolved my installation nightmare. Thank you - Renato!

Thank you! I was restoring my mid-2010 macbook pro and this solved my issue. Hadn't turned it on in a while and date was wrong. Thank you! Hope that video never gets taken down!

Omg this WORKED! Spent a long time trying everything under the sun, and here is the solution! Thanks so much!