Your ZoneAlarm Service is a bit faulty it appears, try going to START > Right Click "My Computer" > Click Properties > "Advanced" Tab > "Start up and recovery" section > "Settings" button > untick "Automatically Restart" then Apply /OK. Next time it happens instead of rebooting it will show u the error up front. Tell us what it says.
OK, when the serious error message comes up again click the "Click here" link at the bottom of it that links to more technical details. then tell us all the bits that it says at the top of the new window.