Hi Juan,
I uninstalled/re-installed PIx64, disabled the antivirus (Vipre Enterprise), and re-ran the updater with the same timeout error. SysInternals Process Explorer showed PI shutting down quickly and the updater launching as expected. As an experiment, I launched PI again to find its PID and then updated my batch file with that PID. Running the batch file as an administrator while PI was still running "paused" the update until I manually closed PI. Then the update ran successfully and much faster than the PI-initiated update. It looks like the updater is timing out, but not because PI is terminating slowly. This same behavior also occurs with the 32-bit version of PI.
Let me know if there is anything else you would like me to try here. Are there any Win 7 Group Policy Objects for installations that might make programmatic requests for admin permissions different than local user-initiated requests for admin permissions?
Roy