Windows sleeps when running a game

Just from today, Windows has started obeying my sleep settings when running a game if I don't have any input on controls, say in free flight.
This has never happened before, and the only thing that has changed is that I installed Tobii Eye Tracker driver and software. It happens even if am not running anything Tobii related.
This is making life a bit tricky!
Any help appreciated.

That's a heck of a setup you're running. About all I can suggest to try is

1.Turn off sleep in power options until you can get to the bottom of the problem. Instead of automatic sleep, manually put it to sleep instead. Go to control panel-power options-next to your selected power plan select 'change plan settings'- change sleep to never. Save changes. (You will have to re-enable sleep to do your testing though.)
To make sleep show up in your power menu, in power options-choose what power buttons do-change settings that are currently unavailable-under shutdown settings put a check by sleep.

2. from administrative command prompt type sfc /scannow to check for file system corruption.

3.Check your update history to see if a windows update applied right before. If so you might attempt to uninstall it.

4. The same goes for Tobii. If that's when your problems started, uninstall it.

5. restore from backup (if you have one). If you don't, use system restore if you have a restore point.

6. Do a repair install Repair Install Windows 11 with an In-place Upgrade Tutorial

Hopefully one of these suggestions will help you..

Thanks for that. Couldn't get anything to work except for disabling Tobii. So, for that and other reasons, I'm giving up on it.

Is the psu strong enough for the system? Anything overclocked?