You should probably have this moved to the Team Discovery forum, as you may get better help there.
However, I am currently running Bonic on Windows 8, and had it running for a long time on Windows 7 without any problems. What I noticed is that the directory does not seem to be correct. Bonic should either be installed to "C:\Program Files\BOINC", or "C:\Program Files (x86)\BOINC". I know Windows 7 really does not like a lot of programs installed off the root of the C drive, so that may be where your problems are at.
What version are you trying to install? The latest is version 7.0.28, and can be downloaded from the link below
Note: Kill Cancer to Reply via e-mail