I ran into the problem with not being able to install programs from the Windows Live Essentials suite like Messenger. The error displayed was:
Error: 0x80070643
Source: Contacts
After some targeted Googling I stumbled on a thread that detailed some fundamental troubleshooting steps I should have completed. In summary:
- Disable third party firewall
- Run services.msc as Admin
- Start the Windows Firewall
- Run installer