Same here. When I use the installer, I get the "Could not set security for file..." error, but after closing it, it confirms that the program loaded anyway. Then when I try to open the program, it gives me the "Required file..." error. I have tried doing both as "run as administrator".
Using the prerequisites (running as administrator) throws me the first error almost immediately and brings things to a stop.
I use Avast, but have it turned off currently. My computer is a year old, so it should not be a performance issue (not that it looks like one).