alcxmntr.exe is installed alongside hardware drivers for the Realtek AC97 audio device.
Alcxmntr.exe is a program that most likely was pre-installed on your computer when you purchased it. This file works in relation to your hardware drivers for your audio devices, like Realtek AC97. The main purpose of this is to be the main driver software for your Realtek AC97 audio device, and this will run in your startup. This program is considered safe and it is not spyware, adware or virus related.
This program is a non-essential system process, but should not be terminated unless suspected to be causing problems.