If your version of ISE has Operations->System 360->Monitoring, then you can see the server's last reboot / uptime under that host, sub-section Monitoring -> System Summary -> Uptime. Please note it won't reflect if someone did a CLI based app stop ISE and then app start ISE. I just did this on one of my lab machines yet it still shows 10 weeks uptime, even though I stopped ISE and started it again from the CLI in the last half hour.
Regards,
David
