The “Not a valid Win32 application” issue can be caused by a couple of things:
File is corrupt, bad, or missing.
Hardware incompatibility (maybe, can happen but not as likely as a bad file).
If the Legacy setup file is corrupt, incomplete or missing, Windows will be unable to execute the file and may generate this error message, or other messages.
1. Reboot your computer and try installing again. If you still get the error go to step 2.
2. Download and save setup file to your Desktop screen. (If you had previously saved this file, delete it before downloading it again.)
3. Next, reboot your computer in Safe Mode and temporarily disable your security programs (firewall, anti-virus, anti-spyware, anti-adware, popup blockers, etc.) as these programs can sometimes remove critical system files from Legacy.
4. Install Legacy using the saved Legacy setup file.