Probably, Rundll error says firewall.cpl is missing ! Please check one by one….
1. Verify ur Internet connectivity;
2. Add the Windows Update Web site and the Microsoft Update Web site to the Trusted Sites list;
3. Make sure that Windows Firewall is turned on, and temporarily disable third-party firewalls;
4. Temporarily disable third-party antivirus software;
5. It is necessary, to ensure that the latest Background Intelligent Transfer Service (BITS) update installed
For better concept and guidance, please visit <a href=”http://support.microsoft.com/kb/920074″>Here</a>, though it is based on SP2, but hope it may help u !