Landlock, USNA Admissions tweeted a few hours ago that their website was having technical difficulties. I actually had technical issues my first time submitting, but I called Admissions and they helped me. A few of my friends from STEM who I keep in touch with also had difficulties. Don't be afraid to be proactive with Admissions and give them a call. They also responded promptly to my email. I used Safari to submit my application on my school computer. If you are having difficulties still, try switching to Chrome, or maybe try another computer, e.g. one at your local library. I think Admissions will have the site up and running soon, so hang tight, as the application is not first-come first-served. Good luck!