DNS poisoning at Google?

Google Safe Browsing and Firefox have marked our website as containing malware. They claim our home page returns no results, but redirects users to another compromised website couchtarts.com. We have thoroughly examined our root .htaccess and httpd.conf files and are not redirecting to the problem target site. No recent changes either. We ran some NSLOOKUPs against various public DNS servers and intermittently get results that are NOT our servers. We believe the DNS servers used by Google's crawler have been poisoned. Can anyone shed some light on this? matthew black information technology services california state university, long beach www.csulb.edu<http://www.csulb.edu>