A senior Microsoft researcher has this week been arguing that PCs infected with a virus should be blocked from the internet. Scott Charney, the corporate vice president for Microsoft's Trustworthy Computing, wrote in a blog post that infected computers should be temporarily banned from the internet until they have been cleaned. The proposal is intended to tackle botnets and prevent malware from spreading across the internet. Charney writes: "Just as when an individual who is not vaccinated puts others' health at risk, computers that are not protected or have been compromised with a botnet put others at risk and pose…