In my specific case I had Windows XP that previously had Spybot Search and Destroy but it had been removed prior to installing Kaspersky Internet Security 2013. Spybot S&D adds and apparently after uninstall, leaves a bunch of well delineated entries in the ..System32/drivers/etc/hosts file. When removed, which I did, Kaspersky no longer complains. Kaspersky product for the first time, flagged this file and these entries as a trojan. So I used Kaspersky to restore the file as hosts.orig and then edited it to remove the spybot-added entries, and then restored as hosts.xyz. Then deleted hosts and renamed hosts.xyx to hosts and rebooted system. Now if you are still running Spybot S&D then I would check the hundreds of entries for consistency and then tell kaspersky to restore hosts and then ignore this until Kaspersky resolves the issue.