回复：

If you have a valid I-94, which you should've received from INS at the time of your status change. You should be fine. It doesn't really matter wheather you have changed your status or not, or how many expired visa stamps you have. As long as u have a valid I-94 for your current status, you should be fine using the automatic revalidation. Check ou these two links below:

http://travel.state.gov/state50158.html

http://www.international.duke.edu/int_contiguous_territory.html