Does this show under you title in Google Results? “This site may harm your computer.” If so get a Google Webmaster Tools account and identified the pages containing the malware the hacker left behind on your web. After you have removed it goto the http://www.stopbadware.org/home/faq#partnerwarnings-remove site and let them know.
I have hear that that as Google clamps down tighter on typical and easier webspamming it drives spammers to engage in more nefarious behaviors to get links, that leads to hacking.
Sometimes you just can’t win