try removing the tool tip from the underlying field (temporarily). does the issue go away ?
I removed the tooltip from the field it was coming from and the issue did go away. But when I added it back, the issue popped up again. Moving the dialog box away from the underlying field doesn't help. It seems to be a remnant of a button I push on the layout which initiates a delete script - it has a tooltip noting the delete action for the current record. Pushing that layout button brings up the first dialog box which asks if you want to delete the current record and there is no phantom tooltip. If you push continue, a second dialog box pops up asking yet again to confirm the delete - it is this second dialog box that has the layout button's phantom tooltip. I have other similar layouts for other tables and this doesn't seem to be an issue on their layouts. Weird
I think you may have some objects stacked on top of one another, or grouped together. In layout mode, try dragging the button to a different part of the layout, or off the layout. Lasso it with your mouse, right click, click on 'Arrange' from right click menu, and see if there is an option not shaded out that says 'Ungroup'. If so, select ungroup, click outside of area, click on the object and drag it out of the way to see what else is there. Once you separate them you can see which ones have tooltips attached. Also, the original spot from where you moved the object, may now have another object with a tooltip.
Or, you can post a clone file with just that layout.