Difference between IE8 for XP and IE 8 for Win 7

Hi,

I have a pc with windows XP and  IE8 (latest patch) AND another pc with WIN 7 and IE8 (latest patch).

The problem is this:

(Win 7 / IE 8) When i click a specific button in a web page it's start a new windows with an Activix program. CORRECT

(Win xp / IE 8) When i click on the same button he dont open a new windows that will run an Activix program.

In both pc i have exactly the same configuration (allow activix....the site is in the trusted site and ALL setting are enabled)

I haven't antivirus on both and i'm totally sure that the activix program doesn't is the problem.

So why in Win 7 i have the pop-up and in win XP no??? What difference there are? I have the same settings and program installed.

Thanks !!!