I had the same problem. McNair being a game time decision, could not log in to yahoo to change to Volek. Yahoo claims you can edit your lineup 5 minutes before the kickoff. Lesson learnt, do it 5 hours before kickoff.
Luckily I won convincingly by a huge margin of about 41 points. He has Chambers to go. I must be the luckiest person, to enter the Super Bowl with 0 production from the QB.
But I agree yahoo sucks and made me upset and tense till I got a huge margin.