MSI file won't install if path is too long

On a clean 64-bit Windows 7 machine, I was trying to load 7-Zip from a usb key.  The 64-bit version of 7-Zip is available only as an MSI file.  Every attempt to install the MSI file by clicking "Install" on its context menu gave me the error message:

"This installation package could not be opened.Verify that the package exists and that you can access it, or contact the application vendor to verify that this is a valid Windows Installer package."

I gave up on the GUI and tried installing from the command line after navigating to the directory containing the MSI.  The command was:

"msiexec /i 7z465-x64.msi"

I had put the command prompt in the directory containing the MSI just so I could avoid typing the full path to the MSI, which would have been

"G:\`Free Programs for New Installs\7Zip\64bit\7z938-x64.msi".

This got me thinking that maybe I was dealing with a path-length limitation.

As an experiment, I copied the MSI to the root directory of  the usb key and tried the install (using the GUI, not the command line) on another Windows 7 machine.  The install completed with no errors.

Seems clear there is a path-length limitation on installing MSI files.