First bug report, so sorry if I just violated 300 rules. I have only been using MIUI for one day so far. Anyway, OpenVPN startup script in /system/xbin/openvpn-up.sh is referencing /system/xbin/bash which doesn't exist. Making a symlink to /system/bin/sh fixes it immediately. Without making the symlink, OpenVPN will connect for a minute or so and then disconnect. Once the symlink is made, it works flawlessly. Experienced on Desire Z.