I have noticed that later Versions of Sony Vegas, especially the 20 version that I have demands a lot more RAM as a minimum requirement than earlier versions. For example, Sony Vegas 13 only demands the minimum of 4GB of RAM while the 20 demands 16GB of RAM minimum. Yours seems to demand 8GB of RAM which should be more than enough to be able to run it x 2 but if you are running a web browser and other power demanding applications on the background, it will increase the chances for it to freeze. Thats why I am upgrading mines from 16GB to 32GB very soon since especially this and Adobe Photoshop’s latest version somehow is demanding more high specs to run and do the same thing as you did in earlier versions, forcing you to upgrade your computer sadly to be able to run it with no issues. I noticed that. Even with a Core i7, you may want to see if upgrading the RAM helps, if it continues, perhaps uninstalling and reinstalling Sony Vegas can help remove any files that can make it freeze and corrupt, good to try every fix you can possible until you find the solution 🙂