This is problematic for sure!
We're trying to get this course fixed so constant crashes will be a thing of the past, however until then, could you try a couple things for me to see if we can't get you on your way?
Comment out all of your code until it's finished, then uncomment it all from top-bottom.
Close, then reopen your browser completely and reset your code as soon as you get into the lesson before it has time to process your code, and follow number 1, above.
Put your browser into "incognito mode", or similarly using "inPrivate Browsing" on Internet Explorer. This will allow you to finish the lesson, then undo the incognito mode when you've completed the lesson, then save and submit your code.
If none of this works then try following this page here!