Upgrading to Pro

There is no "Pro" version of QuickTime Player X, the version you find in your Applications folder. You'll need to use QuickTime Player 7, which may already been in your Utilities folder. If not, you can install it separately. Insert the Snow Leopard install disk, go to the Optional Installs folder and run the Optional Installs.mpkg. You'll be able to select to install QuickTime 7 (it actually installs only the Player) from there.

If you don't have your Snow Leopard install disk handy, you can download QuickTime 7 Player for Snow Leopard here:

http://support.apple.com/kb/DL923

Once you have QuickTime Player 7, run that and look under the File menu. You'll find a Registration option there.

Note that you will need to have a QuickTime Pro code specifically for QuickTime for Macintosh. QT Pro keys are not cross-platform so a key for the Windows version, if that's what you have, will not work.

Regards.

I have the same problem. I had QuickTime X installed and got the message that it should be removed before installing QuickTime 7. But even done so, I get the same message.
What to do?

You're probably not following directions. Do not download the full QuickTime 7 installer; that will not work under Snow Leopard. Install only the QuickTime Player 7, using the directions I gave in my previous post.