Guys, just try and help him with his problem. We don't know the full story here and it just drives people away from this great site.
Did you try what I mentioned with Zone Alarm by the way talkfast123?
My first experience was before it was released. I was involved in the Quake community quite heavily and there was talk on community forums about a new Quake Engine-based game called Half-Life.
I did some research into it and liked what I saw. I then went on to join Halflife.org before it...
I think the only similarity is that technically it may have been inspired by the Houndeye, but I think designer inspiration is as far as the coincidence goes.
Have you tried disabling Zone Alarm just for testing and see if it still lets you? If it does, then it seems ZA doesn't like something.
The windows problem wouldn't affect the game itself, although I would still suggest getting a real copy.