Has the "IsWow64Process" method changed lately - RE: How to check whether the system is 32 bit or 64 bit ?

Hi,

I am using the forum's recommended way (http://social.msdn.microsoft.com/forums/en-US/csharpgeneral/thread/24792cdc-2d8e-454b-9c68-31a19892ca53/) of detecting a 32-bit program running under Wow64 on a 64-bit Vista system, and it used to work - it reported a 32-bit process running under Wow64 on a 64-bit system.  After a couple of months (I don't know exaclty when), this method is now reporting that - when I compile my class as x86 (32-bit) in Visual Studio 2010 SP1 - the method IsWow64Process does not exist in Kernel32.dll.  I am running Windows Vista Ultimate SP2 on a 64-bit HP PC.  I first check if the IntPtr is 8 bits - which it isn't because I have a 32-bit process.  Then I check if the Kernel32.dll is present - it is.  Then I check if the IsWow64Process method is present in Kernetl32.dll - and it is NOT.  I am positive this used to work a couple of months ago.  I moved the methods to a separate class (NativeMethods) to satisfy the Code Analysis tool, but no other changes were made.  If I compile the classe as x64, then the same code reports a 64-bit process because the IntPtr is 8 bits big.

Code extract:

{

 // The Kernelt32.dll module which can contain the "IsWow64Process" method exists.  Now see if the method "IsWow64Process" exists in this module.
                    IntPtr methodHandle = GetProcAddress(moduleHandle, "IsWow64Process");
                    if (methodHandle == IntPtr.Zero)
                    {
                        // The method "IsWow64Process" does not exist, so we are running on a 32-bit system.  This is NOT true as I am running on a 64-bit machine.
                        // Set the system architecture.
                        systemArch = "32-bit";
                    }
                    else
                    { // code which should be reached but is not... }
}

Can the way Visual Studio is told to compile (32 or 64 bit, AnyCPU, Target Platform) affect the way this works ?

Any help appreciated.

Thanks and regards

Keith