What is this crap? I'm running Fedora 14 with Opera 10.63. I guarantee you my computer has no "malware". And if it does, you sure can't detect it from an HTTP request.
Just a guess: I am on a university network shared by lots of humanities majors, many of whom probably browse porn websites on unsecured Windows XP boxes. The company that provides this "service" for Jason sees that many of the computers on this network have been infected by a bot net, and then decides that it's a great idea to block the whole sub net. Now over 5000 people can't read Jason's blog. Is this really effective security? If you want to be really safe, I recommend you block 0.0.0.0/0.