re-start on startup after download

i have read a couple posts on this matter in this forum with the same issue but no solution that could work for me. i downloaded the trial version (vista ready) a couple weeks ago and it would not work. i would click for a theme to load, it would go to through the motions, and then revert back to the old basic windows look. like without the aero or anything. so today i decided to uninstall and re-install the trial to see if i did something wrong during the last install. now...its saying that a firewall is keeping it from loading on startup. i want to buy the program because i know it looks good, but if can't even test it out, i won't. is there something i need to tweak in my settings to get the trial to load?

thanks