I have the UAC turned off. As the log in user, I am the Administrator - no other users on my computer. However, I am using Vista - 32 bit, and I see that you have the 64 bit. and that could be the difference.
The older version of BK 5.2 is not designed for the newer 64 bit. There may be a fix for that, but you would have to read the instructions for install.
Sorry, I can't help you - I have no knowledge in that department.