Sounds like you have a hijacker. If you have an antispyware program on your computer you need to run it. If you don't have one get one. Google has a free one called Spyware Doctor if you can get to it.
Check to see who your default search engine is too. It should be listed under your internet options for "search"
"Until one has loved an animal, part of one's soul remains unawakened..."
- Anatole France