Who is responsible for Grooveshark serving malware?

Visited Grooveshark this morning, selected a Playlist of mine and hit Play All. Was then unceremoniously served Malware. It's your basic security alert redirecting to an off-site domain (www1.servantinspectionon-line.pl) which served a JavaScript alert "Viruses were found on your computer. You need to clean your computer to prevent system crash.".

I've already emailed support@grooveshark.com about this issue, but upon a cursory search noticed that this has been an ongoing issue (since 2009 which I'm assuming is its inception):

http://www.siteadvisor.com/sites/grooveshark.com/msgpage http://onerudedude.blogspot.com/2009/12/beware-grooveshark.html http://www.brucebnews.com/2010/02/grooveshark-malware-warning/

My question would be, after such a prolonged history of serving malware by Grooveshark, who is responsible? The company? Their ad provider? Adobe Flash/Flex? I would presume the buck stops at the top. It's almost as if they don't give a shit.

Am I wrong or is there a problem that's so unsolvable that Grooveshark can do nothing about serving malware for the last 3 years?