The problem you re encountering is indeed a fault with the supplied AVtech H.264 streaming codec. This will not install into IE, Opera, Firefox, Safari or any other browsers. The reason that there are not many people complaining about this iisue is that most do not use the IP software/hardware that's bundled with the video unit.
I'm currently working on a fix for the codec. Once completed, I'll re-post with my email address and I'll send this directly to you.
The issue in laymans terms is that the codec supplied puts explorer into an infinite loop if it's 32bit, and will not install at all on a 64bit version.
Like you, the Quicktime codec works fine, so it's definately not the box!!!
Back soon.
