How to Disable Unknown Publisher in Internet Explorer 8

1. Open the registry editor by clicking 'Start,' typing 'Regedit' into the search box in the start menu and pressing 'Enter.' On Windows XP, click 'Start' and 'Run' before typing 'Regedit.'
2. Navigate to the 'HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies' key in the registry editor by clicking the plus sign to the left of each key.
3. Right-click the 'Policies' key, click 'New,' click 'Key,' type 'Associations' and press 'Enter.'
4. Right-click the 'Associations' key, click 'New,' click 'String Value,' press 'Enter,' type 'LowRiskFileTypes' and press 'Enter.'
5. Double-click the 'LowRiskFileTypes' setting, type '.exe;.vbs;.msi' into the 'Value Data' box and click 'OK.'
6. Right-click the 'Associations' key, click 'New,' click 'DWORD Value,' press 'Enter,' type 'DefaultFileTypeRisk' and press 'Enter.'
7. Double-click the 'DefaultFileTypeRisk' setting, type '1808' into the 'Value Data' box and click 'OK.'
8. Right-click the 'Policies' key, click 'New,' click 'Key,' type 'Attachments' and press 'Enter.'
9. Right-click the 'Attachments' key, click 'New,' click 'DWORD Value,' press 'Enter,' type 'SaveZoneInformation' and press 'Enter.'
10. Double-click the 'SaveZoneInformation' setting, type '1' into the 'Value Data' box and click 'OK.'
11. Restart the computer by clicking 'Start,' hovering the cursor over the arrow to the right of 'Shut Down' and clicking 'Restart.'