You need to provide system information...
We need more details here. What OS? Did you uninstall CS5 before upgrading to CS6? Are you installing using an electronic download or using a DVD Installer?
The error you're seeing is because of an improper install.
Use this tool: http://www.adobe.com/support/contact/cscleanertool.html to clean up all traces of previous installs. Then, re-install CS6 afresh from scratch. That should mostly fix your issue.