When you run out of votes do you lose the ability to comment until your vote bucket is refreshed?
I think I know what brought this question on...
On SO, you currently have 46 Rep. This is still below the Rep threshold of 50 that you need to post comments on other users questions and answers (this info can be found in the FAQ). However, you can always post comments on your own questions and answers even with a Rep of 1.
My guess is that you were able to comment on your own posts, then used up all your upvotes in a day (earning you the Suffrage badge), then tried to comment on someone elses posts and couldn't, wrongly attributing the comment restriction on your casting of votes.
But don't fret, just one more upvote and you'll be able to comment all you want!