Certainly, I can relate to your frustrations with installing the .NET Framework on Windows 7. Here are a few things that might help:
First, try running the installation as an administrator. Right-click on the installer file and select "Run as administrator" from the context menu. This ensures that the installer has sufficient permissions to invent changes to your system.
Secondly, you might want to look into clearing out your temp files before attempting another installation. Sometimes residual files from previous installation attempts can cause issues. You can do this by typing %temp% in the Windows search bar, hitting Enter, and then deleting the contents of the folder that opens.
If these steps don’t work, consider looking at your antivirus or security software settings. Occasionally, these programs can interfere with installations of major software components like .NET Framework.
Hopefully one of these suggestions does the trick for you!