This may help you
1. Disable your anti-virus application, all Norton Add-ons (if any), any real-time protection provided by an anti-spyware application (except for Windows Defender; includes Spybot Tea Timer, SpySweeper Guards, AVG AS guard.exe, etc.), disable any third-party firewall AND THEN enable the Windows Firewall.
NB: You're "working without a net" now: Don't to ANYTHING else online (e.g.,browsing; reading email; chatting) except #4 below until your anti-virus application has been re-enabled!
2. Uninstall "Security Update for Windows Vista [or Internet Explorer] (KB960714)" via Control Panel | Security | Windows Update | View installed updates and reboot.
3. Run Windows Update manually and install any Important updates offered (i.e., KB960714). If a Root Certificates update is listed in the Optional Updates category, install it to take full advantage of IE7's enhanced security.
4. Reboot > Make sure everything in #1 above is enabled again and, if applicable, disable the Windows Firewall and enable (or reinstall) your third-party firewall.