Are you sure the Microsoft Visual C++ Run-time Components are correctly installed and registered?
Have you tried installing the add-in on other machines without QTP or just the one you are having issues with?
If this is a real problem and not just machine specific it kinda kills BPT. If no one can execute Business Process Tests without having QTP installed on their own machine you lose much of the point of BPT.
This means that you may have to update your current Microsoft Visual C++ Runtime component on the machine. To update/install this prerequisite, go to the QTP installation folder or DVD and navigate to the folder: QuickTest\EN\prerequisites\vc2005_sp1_redist
Execute the file vcredist_x86.exe to install this prerequisite.