Can you give us a little more info?
Computer specs (Windows version, amount of RAM, etc.)
Have you applied any of the Sonar 7 Patches (7.01/7.02/7.03)?
What audio interface are you using?
Are you recording to a midi or audio beat?
Are you referring to the vocal mix in your headphones not lining up right when you are tracking/recording (lagging behind), or the finished/recorded vocals don't line up with the project's tempo?