COMODO CIS installation problem

I am having trouble installing COMODO Internet Security System (CIS) and need some help.
To begin I am running a new model Dell with 1.2tb hard drive, 8g memory with Vista 64bit which is running smooth as silk with everything I have thrown at it so far.
- PC Cillin , which was preloaded with a 30 day trial
- COMODO BOClean
- CCleaner
- Spybot S&D
- Ad-Aware
- Spyware Blaster
- Windows Vista Firewall
- Mozilla Firefox & Thunderbird

Downloaded CIS_Setup_3.5.57173.439_XP_Vista_x64 (Vista 64bit version) from the COMODO site. The entire 41.9MB file downloaded OK. Double clicked and unzipped OK. CIS installer opened OK. Clicked NEXT and a CIS installer popup said "An unsupported operation was attempted". And that is as far as I can get. I have tried turning on/off everything I can think of with the same results :banghead. What do I need to do to get CIS to install?
My plan is for this to replace the Vista firewall and then install AVG8 to replace the PC Cillin AV. Any help would be greatly appreciated.