What do you mean it's not being marshaled correctly? As in it won't compile? As in when you try to use the structure it behaves unexpectedly? Did you try using the MasrhalAs(UnmanagedType.R4) or MarshalAs(UnmanagedType.R8) properties? As I recall, a C double is smaller than a C# double or something to that effect. (The reason I think this is because for some reason I think that a C long is actually 4 bytes while a C# long is 8 bytes) So try adding a MarshalAs(UnmanagedType.R4) to your Double. (R4 and R8 marshal floating-point numbers, I2, I4, and I8 marshal integers)

I've just though of a possible method for you. Look at API hooking, hook the SystemParameterInfo function, and tell lies to your software about the underlining flag state. http://www.codeproject.com/info/search.asp?target=api+hooking&st=kw&qm=all[^] http://www.codeproject.com/dll/hookimport.asp[^] One downside I can see is that the function lives in User32.dll, as does the WndProcs for the buttons, menus etc. Its worth a try though! Iain.