Q: Backing up iPhone fails because not enough free space on computer

Greetings,

When iOS 8.4 came out a few days ago, I attempted to install it on my iPhone via iTunes on my PC, because I prefer doing it that way versus over-the-air.  I connected my iPhone and downloaded the update, but during the update process, my iPhone failed to backup to iTunes.  iTunes displayed the following message:

iTunes could not backup the iPhone because there is not enough free space on this computer to save the backup.

Very peculiar.  I have 177 GB free on drive C, which is where iTunes is installed.  That should be way more than enough space for the backup.

So I tried clicking Back Up Now under Manually Back Up and Restore.  Sure enough, the backup failed with the same error message.

My PC:

Sony VAIO VPCEJ28FX laptop

Intel Core i5

8 GB RAM

Windows 7 Home Premium SP1 (64-bit)

iTunes 12.2.0.145 (64-bit)

My phone:

iPhone 5S 64 GB

iOS 8.3

It's been a few months since I last backed up the phone to my PC, so granted, I'm not sure what has changed since then to cause this problem.  I tried everything I could think of to get it working...

I tried restarting my PC.  Same error.

I tried hard-restarting my iPhone.  Same error.

I updated to the latest version of iTunes (12.2.0.145).  Same error.

I tried disabling my antivirus software (Microsoft Security Essentials).  Same error.

I tried running Disk Cleanup.  Same error.

I uninstalled iTunes, Quicktime, and all other Apple software on my PC.  I removed every trace of files associated with this software, including the following folders:

%APPDATA%\Apple Computer

%LOCALAPPDATA%\Apple

%LOCALAPPDATA%\Apple Computer

%USERPROFILE%\Music\iTunes

C:\Program Files\Common Files\Apple

C:\Program Files\iTunes

C:\Program Files (x86)\Apple Software Update

C:\Program Files (x86)\Common Files\Apple

C:\Program Files (x86)\iTunes

C:\ProgramData\Apple

C:\ProgramData\Apple Computer

Then I reinstalled the latest version of iTunes.  Same error.

I tried creating a new administrator account, logging into the new account, and performing the backup from there.  Same error.

At this point, I'm out of ideas.  I don't have another PC on which I can test this.

Any help would be appreciated.  Thank you.