Many problems installing Quicktime+iTunes

Question

(Keep in mind I have windows 7 64 bit)
I need the firmware update for my iPhone 3g, which normally I avoid because I always seem to have a problem with quicktime installing properly. But since a couple up my apps needed to work, I gave in.
When I tried to run the update through iTunes, it installs everything correctly. When I went back into iTunes, I got an error saying iTunes needs Quicktime to run properly. So I uninstalled both iTunes and Quicktime. I ran the Apple Update utility and it did the same thing. So I went to the web site and installed them separately. Again, iTunes 1, Quicktime 0. Now I get an error that I don't have the right file path for the .msi file.
I looked on the forum for this solution and found that I needed the Windows Installer Utility (to remove installer files that failed?) Removed Quicktime.
Attempted to reinstall again, since I can't get in iTunes, which I really need.
Now, a different set of problems occur. Now all of my icons that are shortcuts are Quicktime icons, and I cannot get into them without finding the original file in my directory. At this point Quicktime is not even on my computer any longer. When I try to install it, I get an error saying "Could not open key Unknown\components\(A bunch of numbers) Verify that you have sufficient access to that key, or contact your support personnel." I am on the only account on this PC, but to be fair, I did right click the install file and choose "run as administrator."
Please help!!

Answer 1

It's unlikely taking permissions of the registry key will solve install problems for QT when the initial post referred to a msi file.
This is a rare(ish) variation on a problem involving error messages mentioning missing .msi files that mostly affects 64-bit systems. Although the initial symptom for most people is the missing .msi message, if they use CleanUp, the underlying problem with the registry keys relating to the the Side-by-Side configuration of installed componentry for QuickTime (or Apple Application Support) will come to light.
That's what happened to poor Felix here. (Note in his first post that he's said he's already tried using CleanUp to address the .msi message ... so now the registry key issue has come to light.)
If permissions are just not set properly for the keys, regedit can get us through. But if there's underlying trouble with the ACLs (for example, some people get blank permissions on keys, which are impossible to manipulate via regedit) or other exotica going on, things get messy.