There isnt one built in, but it is easy to use the Windows one, all it takes is a simple API call. Unfortunately only one window can be locked at a time, but you wont get errors if it fails (you just wont get the locking effect).

VB Code:
  1. 'Add this to the declarations section of a form/module:
  2. Declare Function LockWindowUpdate Lib "user32" Alias "LockWindowUpdate" (ByVal hwndLock As Long) As Long
  3.  
  4.  
  5. 'Usage:
  6.              'Lock
  7.   LockWindowUpdate Me.hWnd
  8.  
  9.              'Unlock
  10.   LockWindowUpdate False