It is never ceases to amaze me how many application compatibility issues I diagnose that come down to challenges running 32-bit software on 64-bit Windows!  Flexera is sounding the same drum beat as the primary application compatibility concern when migrating off of Server 2003 and I have to say I agree.

splwow64.exe is the printing subsystem for 32-bit applications. All print drivers on Windows 64-bit must be 64-bit.

So you are preparing your first Windows 64-bit image or just dutifully customizing your own machine.  You copy your traditional set of DLLs to the System32 folder and execute regsrv32.exe against them.  To your horror you receive the error “RegSvr32  The module some.dll failed to load.  Make sure the binary is stored at the specified path or debug it to check for problems with the binary or dependent .DLL files.  The specified module could not be found.”  Has your machine gone insane?  The file is plainly there in the System32 folder.  Let’s put it under the microscope.