Can’t find this setting…

I slipstreamed xp and sp3 onto one of my machines using nlite, and i must somewhere have checked a setting that i cannot now find to reverse. my problem is that the cursor will bring any window over which it passes to the front, covering, for instance, any dialog box that the site or program has brought up in the course of normal use, and requiring me to minimize the big window in order to interact with the smaller one. I’ve been thru mouse settings and cursor settings and i just can’t seem to find this one. I would be grateful for some advice. thanks