I'm looking into this issue right now. Before I've taken care of the site it was hosted by a different ISP. As far I was infromed, things went wrong back then. The site got hijacked and was used for ebay scams once.
Since then I was cleaning up the installation and stripping the drupal setup to the bare minimum. Let's hope I did not miss any malicious extension / code embedded here.
So, could you please let me know which anti-virus software reported "bad" code on this site? This could help track me the problem or identify it as an false positive and sleep well again.