The problem is with the obtuse error message put out by Windows's program loader. It reads, in part, "..is not a valid Win32 application." The application runs everywhere except on Windows XP. Looking for root cause of the problem. It's a very simple application. Only a few lines of code. 

C:\Packaged-Software\32-BIT\Reboot.exe is not a valid Win32 application.
Proposed nature of the problem:
1. The file was downloaded from a website but the download was incomplete.
2. The full file system filename path contains bad characters such blank space.
3. Visual Studio constructed an application that won't run anywhere much less on XP.
4. The supporting libraries are not properly installed (e.g. .NET Framework4, and VCREDIST).
Retorts:
1. The file wasn't downloaded from a website and is intact.
2. The filename path doesn't contain any spaces.
3. The application runs under Windows 8.1.  Also on Windows 7.
4. The supporting libraries are properly installed.
So, what's the problem?  One surely will not discover the root cause from "not a valid application."

Body must be 4 to 60000 characters long.  I had put the code here.  It isn't 60000 character long.  But it validated as if there are more than 60000 characters.  Sorry for the incomplete submission due to website construction

Hi F7H2fw,

How did you develop the application ?

Here is a similar symptom and this may explain the issue somehow:
Setup.exe is not a valid Win32 application
http://blogs.msdn.com/b/vsnetsetup/archive/2012/10/16/setup-exe-is-not-a-valid-win32-application.aspx

I suspect there is a compatibility issue here .
Considering this is more likely a developing issue .It is recommended to ask for help from our MSDN Forum .They are more familiar with the developing issue .If it is possible ,please attach the code in that thread .Thanks for your understanding and cooperation.
MSDN Forum
https://social.msdn.microsoft.com/Forums/en-US/home

Best regards