ITunes will not run. Several error codes. Please help

Question

A couple months ago I tried updating iTunes and received the error "Could not open key:
UNKNOWN\Components\69413F169B198734FA40BC8B73511DB0\108B43C0CEA676640B35306AE7D2 4051.
Verify that you have sufficient access to that key, or contact your support personnel." (take note my key is different than the one above thats just for an example.) So I read and read and finally figured out that my problem came down to permissions for that key. I changed the permissions and voila it installed properly! But now I just tried updating again because I want to get iOS5 on my iPhone4. I received the same error again, "Could not open key..." so I thought heck this is an easy fix and I changed the permissions again and this time it did not work. So then I uninstalled Quicktime, iTunes, and all other Apple software from my computer (which is running Windows 7 btw). I tried to reinstall iTunes and then it went through the install and finally comes to a screen that says "iTunes has successfully been installed on your computer." So I closed that window, restarted my computer, clicked on the iTunes icon and I get a completely different error now. This error is a two-part pop up. The first error window that pops up says:
"The procedure entry point kCMByteStreamNotification_AvailableLengthChanged could not be located in the dynamic link library CoreMedia.dll."
I click OK.
Then I get:
"iTunes was not installed correctly. Please reinstall iTunes. Error 7 (Windows error 127)"
I've tried reinstalling it again and I get the same error. I tried stuff from this thread ( https://discussions.apple.com/thread/2262389?start=0&tstart=0 ) and it doesnt seem to be working. Can someone please help me work through this. I would appreciate it very much, and please explain everything in computer-illiterate terms as I'm not the greatest with computers these days.
Thank you,
Max

Answer 1

OK, so iTunes opens OK in another account so it is a user specific problem.
Just to be absolutely clear, have you carried out the all the user specific steps:
Remobe plugins
Remove preference files
Recreate Library
Check for Content files with issues.
One of those steps usually solves user specific issues.
Something else that you could try is to create a new iTunes library elsewhere on your disk.
Hold down the shift key and start iTunes. Keep holding the shift key until you are prompted to choose or create a library. Select "Create" and create a new library somewhere way from the your music folder eg in Documents - so it is completely separate from your existing iTunes.
Does iTunes Open like this?
If so go do Edit>>Preferences>>Advanced and Un-check "Copy to iTunes Music folder when adding to library". This is to stop iTunes copying your music files when you add to you new library.
Now try adding music from your original iTunes Music folder in stages as in the "Content files with issues" section.
This approach has worked for someone else although they did not say if they stuck with their test library or if they ever found the problem with the original one.