Rush keeps crashing whenever I try to do anything (Macbook Air)

I recently switched to a Macbook Air and since a couple of days ago, I've been unable to use Rush. Every time I launch it, after a few seconds it just dissappears. It seems like this is a problem with a lot of users on here, but how do I solve it? I'm really not tech savvy - part of the reason I'm going with Rush is because it's easy for even technophobes like me to use - so I'd really prefer to not switch over to iMovie or another app unless I absolutely have to. Help!