Here is a video on calibrating the steps per inch. You may need to make some adjustments. Also cut a large shallow circle in a large piece of stock (just profile) and make sure the issue repeats itself. If it is consistent and you are getting nice smooth full dept cuts that are oblong, I would be it is either your steps per inch calibration or the post processor you chose in V-Carve.
Here is a video on calibration: Steps/mm Calibration
Somewhere on this site is information on the correct post-processor to use in V-Carve.