This looks like a local Hips event, so may be better directed to that group.
I'm not sure why winlogon.exe called for an automatic reboot, but if you're pushing HIPS 8.0 via ePO Deployment task and the full HIPS 8.0 Patch 2 installation package (HIP80LMLRP2.Zip), then you can add BYPASSREBOOT=1 to the Deployment task command line switch area. This will prevent the HIPS client installer from calling a reboot. I don't know if this will prevent winlogon.exe from doing it though.
This only works with the HIPS 8.0 Patch 2 and higher full installer; does not work for the RTW or Patch 1 installers.
Thank you for the input. I will try that switch.