Answer
This is usually one of a handful of environment-level causes rather than an actual configuration problem: reinstalling a delivery without first shutting down the running servers, an active security-scanner tool deleting temp files as soon as the installer creates them, antivirus software locking files mid-install, or an underlying OS-level hiccup. Since restarting the Middleware Server resolves it in most cases, the practical takeaway is to make sure servers are stopped (or freshly restarted) and steady before running Install Delivery, and to have antivirus/security-scanner tools disabled on the install machine for the duration of the installation.