I've hit the 40 daily vote limit wall and yet can see on my profile I have 7 votes yet to give to actually reach that ceiling. The votes remain and I am unable to cast them.
According to a recent blog posting:
The daily vote limit used to be 30 votes per day; we’ve increased that to 40 votes per day. But the last 10 of those votes can only be cast on questions.
This does not work for me. I cannot upvote any more questions although I have only done 33 votes today.