Hello there and welcome to BleepingComputer.
Instructions on how to remove the Smitfraud infection can be found in the following self-help tutorial. As stated at the bottom of the page, if this does not solve your problem, please post a HijackThis log in our HijackThis Logs and Analysis
forum along with the report created by Smitfraudfix.How to Remove Smitfraud
If you have any problems carrying out the steps outlined in the tutorial, don't hesitate to ask and we'll try and help you to run them.