theflash1932"2008R2 is a 64 bit operating system that is not as forgiving as 2008x64 on running 16 bit threads."
16-bit applications are not supported AT ALL in 64-bit OS's:
http://blogs.technet.com/b/chitpro-en/archive/2009/04/14/windows-and-16-bit-applications.aspx
While 16 bit applications are not supported there is an emulation that takes place to process 32 and 16 bit threads. It is very limited, but it is functional.
http://msdn.microsoft.com/en-us/library/windows/desktop/dd371688(v=vs.85).aspx