Came across an interesting issue with Windows 2000 Service Pack 4 and Internet Explorer 6 Service Pack 1 today. When we were installing it, it kept on coming up with errors complaining about the cryptography component. The installation source of Internet Explorer was an offline version. Been a few years old.
To cut the long story short, after many tries of trying to reinstall IE with this version with a complete reinstall, I just went to the Microsoft Internet Explorer web page to pick up the ie6setup.exe file to install IE 6 online. Choose the "reinstall all components" or "start from beginning" option if asked. Resuming an installation can cause potential problems.