This comes from a friend of a friend in Texas, who cast an early ballot via electronic voting machine and found that despite voting for the entire Democratic ticket in Austin, the machine told her she had voted for Bush. She immediately got a poll official had her ballot corrected.
Aside from the larger issue of voting machines, urge everyone you know to double-check your vote:
I called the Austin office of the Democratic National Committee, 512.637.1737, and they said that it has been happening a lot. They don't know why but the machines seem more "sensitive" this year and that every voter MUST check their summary as the presidential choice often rolls over to the Republican choice if you vote straight Democratic.
Here is there web site: http://www.democrats.org/ and their main number in Washington, D.C. is 202.863.8000.