I already have iTunes 10.7.0.21 installed and trying to upgrade to version 11.0.1.12

Question

Hello, I recently upgraded to windows 8.  When I run the itunes installer with logging option, the log shows:
Optional package Bonjour64.msi failed to install.
Action 12:21:06: InstallPackage. Starting Apple Mobile Device Support installation...
Optional package AppleMobileDeviceSupport64.msi failed to install.
ExitCode = 1618L
InstallPackages exiting. ==>1618L
CustomAction InstallPackages returned actual error code 1603 (note this may not be 100% accurate if translation happened inside sandbox)
Action ended 12:21:09: InstallPackages. Return value 3.
Action 12:21:09: SetupCompleteError.
Action start 12:21:09: SetupCompleteError.
DEBUG: Error 2836:  The control Back on the dialog SetupCompleteError can not take focus
The installer has encountered an unexpected error installing this package. This may indicate a problem with this package. The error code is 2836. The arguments are: SetupCompleteError, Back,
Action 12:21:09: SetupCompleteError. Dialog created
Action ended 12:21:12: SetupCompleteError. Return value 2.
Action ended 12:21:12: INSTALL. Return value 3.
Any help would be appreciated.
Thanks

Answer 1

I am having the very same issues, admittedly with and older (5 yrs) Windows Vista 32-bit Dell laptop. I had been holding out for a little while on allowing iTunes to upgrade on my computer, and had no issues or complaints with iTunes 7, 8, or 9. But after I allowed it to upgrade today, 10.7 is worthless.
After a few minutes, iTunes pops up with a message regarding insufficient memory, freezes, then crashes. Not even using video, just putting together a playlist of regular file size songs.
I know after reading a bit on the boards that trying to re-install version 9 may cause some things to be lost in translation from 10 to 9, apparently because of some changes in the way the software is set up. Please correct me if that is not the case.
However, I would rather risk it (I have all of my music files on an external hard drive) than to keep having iTunes behave as it is- making the software that I've been using for years worthless to me since it cannot work correctly.
By the by, I know my laptop is ancient by technology standards, but won't be upgrading quite yet.
If you know a reliable source to download the previous versions of iTunes for Windows, I'd be grateful if you could point me in the right direction. I'm fairly computer savvy, and know that I'll need to un-install the most recent iTunes version prior to installing an older version.