Remove your license from B (deactivate it). Uninstall BI. Make sure you have a list of cameras, IP, passwords, etc. Delete the BI folder, you can leave the New/Stored folders if you want. Reboot. Check machine, make sure it is using almost no ram, CPU like 1%. If not, you have an issue with the machine/Windows.
Reinstall BI, do not import any settings, set up cameras from scratch. If you use the same names as before, BI will eventually repopulate the clips and alerts that it finds. Eventually. When I deleted my database for BI, it took over 12 hours.