[CentOS] C7, acpi_als

This is an odd one: I've got a user with a system I built recently, who
comes to me to tell me the systems' frozen. I just looked this time,
before I did an init 3/init 5, and you can't click on anything... except
when I click on the uppermost right, and then I see wired, network and it
flashes, over and over. I finally restarted X.

Now, in the logs, I see a bunch of
Jul 26 11:01:51 <workstation> pkexec[29723]: <username>: Executing command
[USER=root] [TTY=unknown] [CWD=/home/<username>]
[COMMAND=/usr/libexec/gsd-backlight-helper --set-brightness 89]

What little I can find sounds as though acpi_als is for a device that's
checking the ambient light... NOT for a real monitor on a workstation.

The other thing is that she says she's got screensaver set for five
minutes, but it seem to come up much sooner, and then we've got this
issue.

There were no clues in journalctl, or /var/log/messages.

Questions:
1. Anyone ever seen something like this?
2. Any reason I shouldn't blacklist acpi_als?

     mark