I have been using F-Secure as the anti-virus at work since 2004. I have only one time seen a similar thing. It was tied directly to the web filtering component. Once that was uninstalled the errors went away. What version are you using? I have experience with F-Secure Client Security, F-Secure for Workstations and F-Secure for Servers. I have never tried the consumer version, F-Secure Internet Security, but it is closest to the Client Security version, the only difference I know of is the component that allows it to be controlled by a central server. You might also check the firewall as I have had some issues with it at times. If worst comes to worst you might try an uninstall and reinstall. If you are using the consumer version it might not allow you to uninstall single components, but if it does start with the web filtering component. I'll check back here on Monday in case you have any more questions about this. Good luck.
Leland