Astonishingly, the eSlate electronic voting machines allow election officials to define default candidates.

In Austin, they were set up with a default candidate for president. This default selection -- for Bush/Cheney -- overrode previous Democratic votes if voters weren't careful to press exactly the right buttons at the right times.*

Since the Bush/Cheney ticket is the first thing on the page, it is highlighted when the page comes up – and thus, pressing "enter" at that moment causes the Kerry/Edwards vote to be changed to Bush/Cheney.