If using Windows 10 or 11, right-click the setup.exe file, go to Properties, and set Compatibility Mode to "Windows XP (Service Pack 3)".
If you want to move forward with your project, I can help with: for specific Windows versions Locating component libraries for Protel 99SE Converting Protel files to modern Altium formats download protel 99se
If you find Protel 99SE too outdated for your needs, consider these modern alternatives: If using Windows 10 or 11, right-click the setup
