When I first set up a CDK 2 Beta3 server adapter in Eclipse, it had the launch config set up with the wrong path to vagrant - /usr/bin/vagrant instead of /usr/local/bin/vagrant which is the default location on OS X - I didn't notice this and just tried to start the adapter.
Obviously it failed, but I was left in a state where the server was Starting and I couldn't stop it unless I restarted the IDE.

I think it should fail more gracefully.