Have others been able to capture the SystemEvents.SessionSwitch event to detect when the computer has been locked (SessionLock) and unlocked (SessionUnlock)?

I am running on Windows XP, coding in Visual Studio 2005 using .Net 2.0, but so not seem to be catching any events.

I have added the SystemEvents.SessionEnding and TimeChanged just to make sure that I knew waht I was doing and those worked.

But when I hit ctrl-alt-del and say "Lock Computer" nothing is caught.