A strange problem in platforms incompatibility

I found a strange problem between .net application and 16bit application(in nt vm), my operating system is Windows XP SP2.

Case 1: I started a 16bit application under a .net application ( I didn't redirect any standard stream), the 16bit application cannot accept any input, neither output anything.
Case 2: Same as above, but I redirected all standard streams, and specify CreateNoWindow in System.Diagnostics.ProcessStartInfo, unfortrunately, this parameter cannot hide the console window. the other problems are all similar to the above.
Case 3:So I used a middle layer between .net and 16bit vm, I created a process cmd.exe in a .net application with all standard stream redirected, and under the cmd.exe, I started a 16bit sub process, another problem occured, all standard streams are all correct, but the 16bit sub process take down the whole CPU usage.

Maybe this is another evidence about the .net platform is a really *platform* and *environment*. #-_-