For those of us who can't uninstall what isn't currently installed, or who find this advice dubious anyway;HERE IS THE COMPLETE AND ONGOING EFFECTIVE FIX FOR THIS PROBLEM.
And yes, I know I'm shouting, but this seems to need shouting :-(
Look at the post from Computerwild above. Go to his site and download the file he mentions.
Put it on your desktop, and run it every time you update iTunes and still get the error message after rebooting. (You could run it straight after installing iTunes, but then you would never know if Apple had finally fixed this problem or not. If they ever do).
To ensure it can make the necessary changes, run it by right-clicking it and choosing 'Run As Administrator', if this option is present in the right-click menu, otherwise you can just run it normally.
There are two files that can cause the 'boink' problem, and the solution is different for 32-bit OSes and for 64-bit ones.
But the Computerwild solution handles all 4 combinations, and fixes all known problems in this area (or at least all of those reported in this thread, which is about the same thing).
And keeping it handy on your desktop (or wherever) means you can reapply it easily after every iTunes update.
Which is going to be necessary for as long as Apple don't just neglect to fix this problem, but actively break the fix we have, every time they release a new version of iTunes.