Go to www.lavasoftusa.com and download it.
You may have a browser hijack or script, and not necessarily a virus or worm. AV programs and some spyware detectors may not pick up on it.
Here's a good place to start:
http://www.spywareinfo.com/~merijn/downloads.htmlYou may have to run Ad-Aware a few times to get rid of the crap, since many of these seem to run in the background, and you have to CTRL+ALT+DELETE to shut each of them down.
When all is said and done, install a HOSTS file, which should block many of the pesky programs and installer sites:
http://www.accs-net.com/hosts/how_to_use_hosts.htmlAlso locate a good registry cleaning program, to get rid of remnants of the crapware.
And use a secure browser like Mozilla Firefox. But after installing the HOSTS file, even an IE equivalent browser such as Avant Browser should work well (I'd recommend Avant over IE, since it does have some ad blocking).
Good luck! It's a pain in the ass, but it can be done.