more system errors :(

can somebody explain that?
"Event Type: Error
Event Source: Service Control Manager
Event Category: None
Event ID: 7023
Date: 7/19/2005
Time: 3:05:09 PM
User: N/A
Computer: MY_COMPUTER
Description:
The IPSEC Services service terminated with the following error:
The authentication service is unknown.

For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp."
the computer restarted on this event, why?
how can I fix it?, what's IPSEC and can I turn it off?

IPSEC is the security policy agent, are you using a VPN (virtual private network), if not then don't even worry about that error.

You can disable or set IPSEC to manual in Services.