Unable to lock the volume for exclusive access 5

I had this problem earlier whilst trying to burn a DVD using PowerISO. I found an easy solution, but this might work for only some of you.

What I did was;

1. Open PowerISO
2. Go to Tools
3. Under Tools you will see "Convert..." click on it
4. Ensure that the file you are converting, is being converted to an ISO format.
5. Try burning the file again.