api appropriate for win nt4 and win 2000?

I am using a win 2000 machine to develop my code. I am creating a mdi form using a picturebox and placing the form inside the box with api from below. When someone uses win nt 4 to run my program they have this dragging problem when they try to move the form. When they click the titlebar, the form move down about an inch. When release to the place they want, the form goes back up an inch. It gets real frustrating if you are trying to move it to a particular place. Any help? Not win nt 4 compatible? Thanks.


SetParent ConfigTabs.hwnd, picClient.hwnd
MoveWindow ConfigTabs.hwnd, 0, Y, 950, 625, True
ConfigTabs.Show
ConfigTabs.Visible = True

Declare Function SetParent Lib "user32" (ByVal hWndChild As Long, ByVal hWndNewParent As Long) As Long

Declare Function MoveWindow Lib "user32" (ByVal hwnd As Long, ByVal X As Long, ByVal Y As Long, ByVal nWidth As Long, ByVal nHeight As Long, ByVal bRepaint As Long) As Long