There have been reports of Machines switching the person you voted for over to a 3rd party or over to McCain if you voted for Obama or straight party ticket. Some people do not catch this and accept it.
Make sure it has not done this before you hit accept and also ask for a print out and go thru it page by page to make sure it got yours right. If you see anything funny, alert the election official so they can correct your vote and have the machine fixed.
If you show up to vote and find you are not on this list, read this to know what to do:
http://www.huffingtonpost.com/robert..._b_138390.html