Hello Katsuji Hatakeyama,
Have you attempted some basic troubleshooting steps, such as reinstalling search package, rebuilding the index, and commands like "sfc /scannow" and "chkdsk /f" to check any corrupted files and disk errors?
Are there any error messages or events that seem related to the freezing issue in the Event Viewer? You may check the "Windows Logs" and "Application" for any relevant error messages.
Does the issue still occur when the server is booted into Safe Mode? Try to boot the server into Safe Mode and see if the issue persists.
You consider using Reliability Monitor to fix Windows problems: https://www.thewindowsclub.com/use-windows-8-reliability-monitor
If the above troubleshooting steps don’t work, you may try some advanced troubleshooting steps.
Run tools like Process Explorer and Process Monitor, to identify any abnormal behavior or errors occurring during the freezes.
Regards,
Karlie