Mouse exit only works going up?

Running into a strange interaction, and I hope someone can help...I have a screen with a mouseover button, the usual two actions to show a text popup on mouse enter, hide on mouse exit.The screen also has a click button (below mouseover area), to display a third text area.If I mouseover running my mouse upward (vertically towards the top of the screen from the mouseover button), the hide works fine. However, if I mouseover down the screen (towards the bottom, and the second button), the hide doesn't work -- the shown text remains shown.I've tried a variety of sequencing of the icons, with no improvement. Any ideas? This is driving me nuts! (Admittedly a short drive...)