I've got exactly the same problem. I can't figure a way to fix it. I re-installed them all using candybar, but they're not being recognised. I;ve tried a relauchn finder, and a restart, but it won't help. not sure what else to try. Is there a way to uninstall the update?
I'd also say that the speed of loading files in quicktime has decreased, I've got 2GB ram in my Macbook, and they used to open after a few seconds tops. Now, they're taking 15 seconds plus.