My PC seems to have been infected with something that has taken over my Internet settings. The Internet Explorer home page has been changed to a search site, and I can't set it back. Every time I connect to the Internet, my screen gets filled with pop-ups (many pornographic), and I can't make them go away. My anti-virus software is up to date but doesn't find anything to remove. I tried Spybot and Ad-aware, but neither of them have solved the problem. Any ideas?

It sounds like you have been compromised by the Cool Web Search bar or one of its variants.

There are tools to help clean your system. Get the Cool Web Search Shredder. This will try to remove all the registry entries and files associated with the Cool Web Search bar.

If Cool Web Search Shredder fails to run when you start it, you may need the Cool Web Search Smart Killer removal tool; run that to disable Cool Web's ability to kill the Shredder removal tool.

Once you have regained control of your system, see this article to learn how to prevent similar browser hijacking problems.