iTunes 12.1.1 installation errors and resolution (Win 7, 64 bit)

I am providing all of the installation errors I had experienced

and all of the methods I had tried until I finally came up with a solution.
Hopefully the details will help you see if your situation has similarities

which hopefully will make this post helpful in terms of a solution.

PART ONE: INSTALLATION ERRORS

I received the following installation errors

when attempting to update to 12.1.1

and later once I uninstalled and attempted to reinstall 12.1.1.

I used this link for the download:
http://www.apple.com/itunes/download/?cid=wwa-us-kwg-music-itu
> itunes 6464setup.exe

I then tried this link:
http://support.apple.com/kb/DL1614
> itunes 12.1.1 64 bit

Again 6464 in the name.

After uninstalling the iunes,
I discovered under add/remove programs:
apple application support 32 bit
and apple support update
I deleted these and restarted the PC.
I then tried reinstalling a NEW version
from the second link above.

Opened download iTunes 6464setup.exe >
Windows installer> iTunes > welcome to itunes
> next > installation options > install > user account control
> yes > next > (error message via pop-up window):

ERROR MESSAGE ONE

"An error occurred during installation of assembly Microsoft VC80 CRT Type ="win32",
version = "8.0.50727.6195".publicKeyToken="1fc8b3b9a1e18e3b"
processorArchitecture ="amd64".

Please refer to Help and Support

for more information.

HRESULT: 0X80070091"

> OK > iTunes > Status: Starting services >
(error message via pop-up window):

ERROR MESSAGE 2

"Service 'Apple Mobile Device Service' (Apple Mobile Device Service)
failed to start. Verify that you have sufficient permission to start system services"

SIDE NOTE

There was a USB cable connected to the PC to charge the iPhone,
but the iPhone was not connected. I detached the USB cable from the PC in case it's relevant.

(I did not reattach the USB cable until I finally got a copy of itunes to install. You will see later in this post below.).

I then clicked Retry.

ERROR MESSAGE 2 AGAIN

I received the identical 'Apple Mobile Device Service' error as above.

I then clicked Ignore.

iTunes > Status

> User Account Control pop-up window)
> Do you want to allow to install Apple iTunes>
Yes >

> Congratulations > Finish

> (iTunes pop-up error window):

> iTunes Helper

ERROR MESSAGE 3

a)
"Apple Application Support was not found.
Apple Application Support is required to run iTunes.
Please uninstall iTunes and install iTunes again.
Error 2 "

> (iTunes pop-up error window)

> iTunes

b)
"Apple Application Support was not found.
Apple Application Support is required to run iTunes.
Please uninstall iTunes and install iTunes again.
Error 2 (Windows Error 2)"

> OK > OK

ERROR MESSAGE 4

I received all of these errors above

when I had tried a fresh install before returning to the forum to search for answers.
When I had first tried a fresh install, I didn't get as far as the Congrats.

I only got as far as the first and second error listed above
("An error occurred during installation of assembly Microsoft VC80 CRT Type ="win32"...

AND Service 'Apple Mobile Device Service' (Apple Mobile Device Service").

Clicked on iTunes icon on desktop

ERROR MESSAGE 5

I receive the (iTunes pop-up error message window)

error 2 windows error 2 (identical to what's listed listed under 3b).

PART 2 - INSTALLATION RESOLUTION

The issue finally is resolved.

HERE IT IS!!!

1) Uninstall iTunes

2) check remaining Apple programs

(click control panel > programs > uninstall)

> check the listed Apple programs

Apple Application Support 32 bit,
Apple Mobile Device Support,
Apple Software Update,

Bonjour

3) Locate and save the correct file version of iTunes for your OS and System.

In my case, it's Win 7.

You must check for the System Type.

Computer > right click to properties > system type.

In my case its 64 bit.

The 32 bit installer is namediTunesSetup.exe,

while the 64 bit installer is named iTunes64Setup.exe.

I learned that some folks had experienced issues with

the 64 bit installer on the Apple site whether it's

because they had downloaded the 32 bit

when they needed the 64 and therefore

couldn't complete the install or in my case,

what appears to perhaps be a corrupted file that stated 6464 in the .exe file name.

This lead me to believe that finding the file with the correct file name and

correct file size to prove it authentic for that version would likely be part of

the solution if not the solution. File Hippo is one suggested means to locate the file.

I locate the iTunes download "iTunes64Setup.exe" that matched the size of the file

to a valid copy of that version of ITunes and I set it aside.

4) I then made sure that all old copies

and remnants of iTunes and Apple software

has been uninstalled by checking add/remove.

Then C: program files

and then C: program files (x86),

then running CC Cleaner,

then cleaning the registry using CC Cleaner

and then checking Tools under CC Cleaner.

***I discovered under Tools that there were remaining Apple files listed

after the uninstall of iTunes and other files had taken place under iTunes***

I visit tools under CC Cleaner and deleted the remaining Apple files

including Apple Application Support, Mobile Device Support, and Bonjour,

***but I leave the Apple Software Update folder as is, in tact***

under C: Program files (x86) and Tools of CC Cleaner and under Add/Remove.

5) I restart the computer, install the new copy of iTunes 12.1.1 (64 bit),

iTunes64Setup.exe, and it installed with zero errors.

Hope someone will find this useful. Good luck.