Harris County (where Houston is located) uses the same type of voting machines as Travis County (where Austin is located).
In Texas, you can override a straight ticket vote on individual races. That is, the straight ticket vote only has an effect for a particular race if you don't pick anyone. If you were using a paper ballot, you could leave the rest of the ballot blank - and you would know why the rest of the ballot was blank.
On the voting machines this was confusing some voters. They would vote straight ticket, and then go to the next page of races, and it would show that they hadn't voted for any candidate. So they reprogrammed the machines, so that if you voted straight ticket it would then show that you had voted for each candidate of your party.
To prevent overvotes, the machines are programmed to erase your vote for one candidate if you vote for another. So if you voted a straight Democrat ticket, and scrolled to the president page, it would show:
President
[ ] Bush - Rep
[X] Kerry - Dem
[ ] Badnarik - Lib
[ ] Write-In
In Harris County, the machines were originally programmed to move the selection cursor to the first choice on a race, but now they move it to the label for the race, and you then have to scroll to a candidate before you select. It sounds like that in Travis County, they may still be using the other method (or maybe because the select won't do anything while cursor is on the label, and the voter was scrolling to the next race).
If the cursor was on "Bush", and the voter selected it, the Bush box would be marked, and the Kerry box was unmarked. The cursor would also advance to the next race on the ballot. This is undoubtably what was happening.
For a straight-ticket Republican voter, it is less of a problem. The way you "unvote" on a race, is to select an already selected choice. So if you had voted Republican, and then came to the presidential race, and accidentally unvoted Bush, your straight ticket choice would override the lack of a vote.
Another source of confusion was on races where there was no candidate for your straight-ticket-party (e.g. if you voted Democrat, and a race had only a Republican candidate, or a Republican candidate and a Libertarian candidate). If you only voted straight party Democrat, you would have undervoted that race. Democrats complained that this was confusing voters.
The solutions that the Democrats have proposed, essentially ignore state law. They either want the machine to scroll past all races if you vote straight-ticket, preventing ticket splitting; and they don't want to have a warning if your undervote is due to a straight ticket vote. The real solution would be to eliminate straight-ticket voting, but Democrats don't want that to happen.
