>You said you tried _vfp.hWnd and _screen.hWnd and you confirmed it doesn't work. I can not find any way to get a hWnd that DOES work. It seems that the lockwindowupdate() function just does not work on XP and using either VFP7 or VFP8. It worked for me under NT.

Matt,

I tested your code with VFP7 and WinXP Pro and it seems to be working. Try to test a value, returned by LockWindowUpdate(). It should be 1. If not, you can get an error code using API function GetLastError():
Declare Long GetLastError in Win32API
Only one window in system can be locked at a time. If any window is already locked your call wouldn't work.