If you hit CTRL-ALT-DEL on ESX 4 console, the server will reboot even if there are running VMs and it doesn’t matter if the server is not in Maintenance Mode.

To disable this yourself:

1. Open /etc/inittab (vi /etc/inittab)

2. Search for “CTRL-ALT-DELETE” or “ctrlaltdel” (hit escape, “/”, and type “ctrlaltdel”)

3. Comment out the line “ca::ctrlaltdel:/sbin/shutdown -t3 -r now” with a # symbol. (hit escape, “i”, “#”)

It should look like:

# Trap CTRL-ALT-DELETE 

# ca::ctrlaltdel:/sbin/shutdown -t3 -r now

4. Save and exit the file (escape, “:wq”)

5. To make this take effect without a reboot, run the command:

init q