Usually 2 types of problems causing this error:
1. Spaces or illegal character in the Talend installation path
2. A corrupt/incomplete Java installation
downloaded it, unzipped it using 7z and copied the entire folder from a network drive onto my local drive.
Did you download your Talend Data Integration Build Version - v5.3.1 product from Talend Official Website? http://www.talend.com/download/data-integration
Is your installation path too long? Unzip it to a root drive, e.g. 'D:\Talend-5.3.1\studio\.
Is it still not working when you create a new project instead of importing a demo?
Standard Sun JDK
Is there any more error log which is located in <Talend Studio installation path>/workspace/.metadata/.log .
Caused by: java.lang.ClassNotFoundException: org.talend.designer.esb.webservice.WebServiceComponentPlugin