Two things:
1) What operating system are you using? What version of CVI are you using? Ensure that the compiler define "/DWIN32_LEAN_AND_MEAN" is configured in Options>>Build Options.
2) It looks like for some reason it's pulling the winnt.h from C:\Program Files\Microsoft Visual Studio\VC98\Include rather than C:\Program Files\National Instruments\CVI81\sdk\include. Ensure that your include path is not setup to search in the VC98 directory (Options>>Environment).
Additionally, please note that if you are using "windows.h" inside of your application, ensure that it is the first include file in your applications.
Thanks,
Andy McRorie
NI R&D