The error message you see is generated by windows and appears only when trying to run a 16-bit program on an x64 system or an x64 program on a 32-bit system.
So either you have 32-bit windows installed, or the download is damaged and windows thinks it's a 16-bit executable.
1. Check system information to make sure you're not running a 32-bit version of windows. If you do, download the drivers for it.
2. If you have x64, the download is damaged, redownload, and use a browser/download manager.
As a general rule, always avoid auto detect programs. They're not clever at all.
CPU: AMD Phenom II X4 810 @ 3120MHz | RAM: Kingmax 2x2GB DDR2 800 @ 833MHz| MoBo: MSI K9A2 CF v1.0 (BIOS: 1.D)| GPU: Asus HD 6850 1024MB (DirectCu) @ 835/1135MHz | Display: L24FHD | PSU: PC Power & Cooling Silencer 750 Quad | OS: MS Windows 3.11 Pro x64