Hello everyone !
I have Windows 7 / 64b, and as far as I have read in other various posts, Quicktime has not developed yet a 64b version. CS6 needs Quicktime 7+, so i just installed Quicktime 7.1 and it works. Mostly, this problem comes from the fact theat on Quicktime website, you can only download the latest version. (7.73.80 etc)
Hope to find this usefull.