i can vouch to this one.

it has only happened to me twice, but i am *very* precise with my actions in mirc. knowing good and well i did not click always on top, i toggled the feature several times to see if it would affect it... no go. i made the script i'm using, so i know for a fact that it isnt the script doing it.

to make a long story short, the only thing that i could do in order to keep mirc from stealing the top window was to reboot. i think it may have something to do with an installer program i used while mirc was open though... however, i can not be too sure.