http://support.microsoft.com/kb/923737

http://www.mytechguide.org/9560/reset-internet-explorer-ries/

certutil -setreg chain\EnableWeakSignatureFlags 8

Disable Protected Mode:

1. Click the Tools icon in Internet Explorer
2. Click the Security tab and uncheck the checkbox beside Enable Protected Mode (requires restarting Internet Explorer)
3. Click Apply, and then click OK.
4. Close all open Internet Explorer windows, and then restart Internet Explorer.