A company called Xupiter has created a toolbar for Internet Explorer that, if your security settings aren't set high enough, will automatically install itself into Internet Explorer, change your default start page to their homepage, redirect all of your search engine queries to their site, and possibly much more. The story is
here.
The company does have an uninstaller, but many folks report that it doesn't work. There are uninstaller programs mentioned in the article linked above. Personally, I use
Mozilla as my browser, which is the freeware and not choked with ads version of Netscape. The other thing that's cool about Netscape is that if it crashes (which it's very stable, but it can happen) it won't take down all of Windows on you like Internet Explorer does. It will also import your existing Internet Explorer bookmarks.
Just food for thought.