Ok, first, are you running windows 7? If you are, install in ANY directory EXCEPT 'program files.' Need special permission (Administrator access) for that file, and can be a pain. If you must use 'program flies,' than be sure you have set yourself with appropriate permissions from whereever you are acccessing your PC.
This might help... I'm a newby.. and a lot of people are away for the 4th holiday. Hope it helps....