Websites down EC2 inaccessible via SSH CPU utilisation 100% last few hours - what should I do?

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http://serverfault.com – I can afford 15 min or less down time. Should I then (in AWS console) reboot my instance or create an AMI image from my instance and launch it and associate my elastic IP to the new instance or "launch more like this" Background on what may have happened to my ec2 The last time I made changes for 21 hours ago. A cronjob to create snapshots ran around 19 hours ago and it has been running for a long time. Google Analytics shows traffic to my websites such as kidlander.sg has been nothing exceptional. Is there any other actions I should take or better options I could have? (HowTos)