If you create a new AWS account and try to start EC2 instances, once in a while you may get the following errors.
This account is currently blocked and not recognized as a valid account. Please contact aws-verification@amazon.com if you have questions.
Alternatively you may get the following error when you try to start an EC2 instance with more than 1 vCPU
You have requested more vCPU capacity than your current vCPU limit of 1 allows for the instance bucket that the specified instance type belongs to. Please visit http://aws.amazon.com/contact-us/ec2-request to request an adjustment to this limit.
Both these issues can be easily fixed. You need to contact AWS support through support console and ask them to activate your account in the region you want. You then need to request to increase vCPU limits for that region. Following video explains how to do just that.
In both cases AWS is trying to prevent any fraudulent activities with newly created accounts. This activation is one time process and is not a huge burden.