Compiling with the large exe option would not remove the possibility of the problem Deana mentioned. In fact, it makes it more likely the cause. Windows 7 has been around for over 4 years, is the most commonly used version of Windows, and the two functions you are using are two of the most commonly used functions in WIL. If there was a problem with either of those functions specific to Windows 7, we would have known about it a long time ago.