My WordPress Blog Hacked with Redirect!

HELP! My traffic has dropped from 1.5 to 2k visitors per day to nearly zero because of some hack or script that was installed without my knowledge, either on the server somewhere or in my WordPress code. When visitors click on my posts through Google they end up being redirected to an ads site somewhere else. If you search google for “watch the office online” you should come up with this post somewhere in the top 3:

• http://www.mymindwanders.com/blog/2007/07/14/watch-the-office-online-the-best-site-for-online-streaming-of-the-us-version-of-the-office-is-sidereelcom/

Now when you click on it it should redirect you. However, http://www.mymindwanders.com and http://www.mymindwanders.com/blog is unaffected. It will only redirect you once because I think it logs who is clicking and won’t redirect you multiple times, which is why I can no longer see what ad site is popping up. Can anyone help??