VB.NET code for detecting system events

Hi, For? a small hobby project of mine I need to be able to detect when certain system events happen such as: * the user locks the screen/workstation * the user unlocks the screen/workstation * the user sends a logoff command to the OS * the user sends a restart/reboot command to the OS * the user sends a Shutdown command to the OS I am doing this project in Visual Studio 2010 and VB.net so VB.net code is preffered. All I need are the code pieces / samples to do the above. You don't have to deliver an application that has any functionality other than contain the code to detect the abovementioned. Best Regards, Henrik