Another person with an install problem

After playing the demo I bought Sins.  I have uninstalled the demo, and try to install the game from the DVD.  I get this message:

"Error

Error writing to file:  C:\Program Files\StardockGames\Sins of a Solar Empire\FirewallInstall.exe.  Verify that you

have access to that directory."

Again, the directory does not even exist, or the file.  I have run a registry cleaner, installed and uninstalled the demo again, run a virus check, everything.  This happens every time that I do that.  The last program I tried was ccleaner, cleaning hte registry and all the old installs.

I am the only user of the computer, and the administrator.

Any help out that would be appreciated.  I'm turning it off for the night, so I'm hoping someone has something magic come up by morning.