To my surprise I just faced a similar problem on Windows when I was implementing additional user-based isolation for my p2p cloud gaming service (the main one i

To my surprise I just faced a similar problem on Windows when I was implementing additional user-based isolation for my p2p cloud gaming service (the main one is VM boundary). Apparently when you create a process as another user on Windows by default the new process inherits parent's environment variables even though they belong to different users. That includes user-specific paths such as $TMP or $APPDATA. So most programs immediately fail because they try to write to the temp directory of parent's user. Solved this with a combination of LoadUserProfile and GetEnvironmentBlock.