1. Run repair on SI4 by going to START > Control Panel > Add/Remove > System Integrator > Change/Remove > Repair - Follow the prompts until finished.
2. Uninstall Business Manager, then re-download the latest version and re-install it.
Now launch SI4 and you should be good to go. Make sure that your client version is 4.6.174 also.
Download for SI4 (Business Manager)