Originally our svn was using a single repository and we changed it to use a collection of repositories. We were still using the same subdomain "svn.server.com" with the main difference that our collection is now svn.server.com/repos/
SmartSVN stored the old url "svn.server.com" and seemed to ignore the new supplied url during checkout (svn.server.com/repos/TEST)
The solution is simple.
SmartSVN > Preferences > Authentication
Delete the old record and then try to check out again.