The Security Mentor

Zone Alarm is a popular firewall program. One of its features lets you block popup and popunder ads, or even (at its strictest setting) banner ads.

Now that bad guys are using banner ads to spread infections, blocking ads is a security feature and not just a convenience feature.

Unfortunately Zone Alarm has a bug. If you turn on ad blocking (it's off to start with), you open yourself to a bug in which your computer can lock up if Zone Alarm tries to read certain kinds of web content.

For now your best move is to check regularly for the upcoming fix. Open Zone Alarm, go to the Overview section's "Preferences" tab and hit the "Check for Update" button. If you're running FireFox or any other alternative to Internet Explorer, you're safe from getting an infection from a banner ad and you could safely turn off ad blocking altogether if you want to.