- Be sure you have a firewall installed (Windows XP Service Pack 2 includes a built-in firewall).
- Be sure you are running anti-virus software with the most up-to-date virus definitions available.
- Be sure you are running adware/spyware protection.
One option is Ad-aware SE Personal (free) which is designed to provide "protection from known Data-mining, aggressive advertising, Parasites, Scumware, selected traditional Trojans, Dialers, Malware, Browser hijackers, and tracking components."
To locate, go to http://www.lavasoftusa.com/software/adaware/ and click on the "Download Ad-aware here" button on the right.
Or you can find the software on http://www.download.com/ at http://www.download.com/3000-2144-10045910.html?part=69274&subj=dlpage&tag=button
Ad-aware is one of the first applications built to find and remove adware and spyware. It has the ability to scan your RAM, registry, hard drives, and external storage devices for known data-mining, advertising, and tracking components. This application cleans your system and provides a higher degree of privacy (and more efficient computing) while you surf the Web.
Ad-Aware SE Personal Edition can also scan for known and unknown/possible browser hijackers.
NOTE: Ad-aware is NOT free for commercial or business purposes.