Currently Being ModeratedJul 23, 2013 9:37 AM (in response to PhDflops)
Thank you for all the information you provided about the installation issue you are experiencing. I recommend reviewing the steps in the section titled "Troubleshooting an unsuccessful installation" in the following article:
I also recommend backing up any data that you want to keep. If you are doing a regular install, it shouldn't erase your content, but it is always a good idea to keep valuable information backed up.
Thank you for using Apple Support Communities.