Can't connect iPhone, can't install new iTunes
Once again, I'm having issues with my iPhone and iTunes for Windows. Despite having connected successfully just a couple of weeks ago to backup, sync, and rearrange my apps. when I connect today I get the message "The iPhone [iPhone 6 Plus name] cannot be used because it requires a newer version of iTunes. Go to www.itunes.com to download the latest version of iTunes."
The iTunes version is 12.1.2.27, 64bit.
The computer is a 2-year-old Dell AIO with an i7 processor and 16GB of RAM, no slouch, with Windows 8.1.
The iPhone 6 Plus is running iOS 9.0.2
So I dutifully go to download the latest iTunes installer. When I try to run it, nothing happens. In Task Manager, I see an iTunes Installer process that's taking no CPU and 0.1MB of memory.
When I try to run the installer as administrator, I get the UAC dialog, which of course I allow, but in this case, an iTunes Installer process doesn't even start.
I have done a full shut down and restart and tried installing with nothing else running. No dice.
So, 2 questions:
Why is my current version of iTunes not able to work with my iPhone?
Why do I consistently have so much trouble installing iTunes for Windows? (This is far from the first time an iTunes upgrade has been seriously problematic.
Note: If the "solution" is to uninstall and reinstall iTunes, why should that work? When I worked at Microsoft Product Support back in 1990, when customers had serious problems, the lazy techs trying to keep their call volume up basically dismissed customers by saying "reinstall Windows." Such a "solution" does nothing to identify and solve what caused the problem in the first place, even if the result worked. While I want to get iTunes working again with my iPhone (just got a bunch of new ELO CDs I'm ripping to put on my devices), I want more to know what the actual problem is that's preventing me from accomplishing my goal.
Dell AIO-OTHER, Windows 8