I was having problems installing it a few days ago. Try uninstalling whatever you have already, and delete the install file. Restart your comp and download the installer again and try again.
I had to do that a few times (4-5) before it worked...it was really weird. GL
What's your opperating system? Are you using Vista? If yes, then look on their website. There's a section that explains the steps for installing the software on Vista! Here's the link to that page: