After you install a UPS device, in the UPS tab of the Control Panel / Power Options applet, when you restart your computer, it immediately shuts down again.

If the COM port that you specified for the UPS is in use by another device, such as a modem, you may experience this behavior.

To fix this problem:

1. Disconnect the other device that is using the same COM port.

2. Start your computer and reconfigure the COM port usage to avoid this conflict.