The Definitive Guide to Data Quality
I have resolved the issue. The steps I took:
removed java 7 and 6 from my pc,
reinstalled java 6 only,
deleted the configuration folder under C:\Talend\Talend-Studio-r90681-V5.1.2,
Reloaded a new configuration folder from the zipped download in to the previous location.
Now I have a working connection.