Hey Matt -
There is a long standing bug that pops up on occasion with the metronome count in. If your track is playing back and lining up, 1 measure late, go to metronome options and disable the count in, or set it to "0" measures.
If it is literally a 1/2 second behind, then I am out of ideas. Check your latency settings on your sound card and see what they are set to.
Your OS and version of Sonar should not matter, but it may make it easier for someone to explain the exact steps to take when searching for the problem, or solution.