CS5.5 and CS6 can co-exist on the same computer. No need to uninstall.
Why 10.6.4? Download the Combo Updater, and go to 10.6.8, unless you have a good reason for not doing so.
You didn't list your computer spex. Do that, please.
Jim Simon wrote:
1) CS6 was designed for Lion (10.7 or greater).
Maybe so, but 10.6.8 is an Adobe approved OS, and Pr is working more or less fine for me on that version.
Back up and running.