Task manager will do this, just go to answer #2 on the below link, it has exactly what you want, except....
- Line item 9 should be event ID 10001 (disconnect) instead of 10000 (connect)
- Line item 12 should be the command "shutdown /s/f", or just create a batch file called shut.bat that has one line, the command "shutdown /s /f" (no quotes), and broswe to your file shut.bat when you get to Line item 12
networking - How can I run a script when my network connection changes? - Server Fault
Task manager will do this, just go to answer #2 on the below link, it has exactly what you want, except....
- Line item 9 should be event ID 10001 (disconnect) instead of 10000 (connect)
- Line item 12 should be the command "shutdown /s/f", or just create a batch file called shut.bat that has one line, the command "shutdown /s /f" (no quotes), and broswe to your file shut.bat when you get to Line item 12
networking - How can I run a script when my network connection changes? - Server Fault

Its right there in my win7 task scheduler. No idea what the windows xp task scheduler looks like.there is no "Triggers" tab
Its right there in my win7 task scheduler. xp can't be too different, but this is a win7 forum, so....and I don't understand this part : Select "Log:" => "Microsoft-Windows-NetworkProfile/Operational"