OOTP 8 Free won't install

[Yeldarb]

I have downloaded the setup file and it will not install. I run the downloaded file and the setup or unpacking (whatever it's supposed to be doing) window comes up. Just as the status bar gets all the way to the right, one of three things happens:

1. An error pops up telling me the window tried to close in an unusual way and the installation is terminated.

2. I get an error message telling I don't have all the necessary files.

OR

3. The setup program stops responding and Windows recognizes this and terminates the program.

This is happening on both my laptop, which runs Vista, and my desktop, which runs on XP.

I have downloaded the setup file from both the main OOTP 8 site and from the link that was included in the promotional e-mail, I get the same results. It also happens whether I'm directly linked into my internet or accessing it through my wireless router.

Any ideas? Any solutions?