Google - distributing malware error - URGENT

I'm getting this error on my client site when searching on GOOGLE with specific keyword. ERROR This site may be distributing malware. Google users will see a warning page when they attempt to visit pages within this site. You can visit the Google Safe Browsing diagnostic page for your site for detailed information about the problems we found. Help Loading... If you have experienced this error before, and know how to resolve this ASAP, please post. I will provide you with my client name and keyword.