[Oracle] 12c install error INS-30131

While trying to install Oracle 12c on Windows, in the very first steps, you may encounter an INS 30131 error saying:

[INS-30131] Initial setup required for the execution of installer validations failed. Cause: Failed to access the temporary location

This may happen because upon installation, Oracle's trying to access the C drive as a network share but fails to do so. To fix it, make sure you can actually access the C$ share on your machine.