From the Windows OneCare Team Blog’s “Windows OneCare Firewall Ã¢â‚¬â€œ KeepinÃ¢â‚¬â„¢ it Green, Part I“:
Through a combination of surveys, emails and customer communication, we maintain a close watch on the Ã¢â‚¬Å“healthÃ¢â‚¬Â status indicators, such as, percent of users with anti-virus out of date, or the ratio of customers that are regularly backing up files.
… Recently, we have noticed a slight increase in the number of people turning off their firewall, with a corresponding decrease in the number of green machines.
Based on our investigation, there are four primary reasons people are turning off their firewall.
1. Do not think a software firewall is necessary
2. Do not like the (sometimes incessant) pop-up dialogs
3. An application failed to install with firewall turned on
4. An application fails to work with firewall turned on