UnsatisfiedLinkError when running Grails/GWT app in DevMode

Question

Using Grails 2.1.0 in GGTS 3.1.0 with gwt plugin (gwt:0.7.1) and dto plugin (dto:0.2.4). I have a simple DTO object:

public class TestDTO implements grails.plugins.dto.DTO {
    private static final long serialVersionUID = 1L;

    String text;

    // Required for DTO serializer
    public TestDTO() {}

    public String getText()
    {
        return text;
    }
    public void setText(String text)
    {
        this.text = text;
    }
}

When I compile the gwt modules and launch the app, it works fine. However, when I launch DevMode, it fails with a java.lang.UnsatisfiedLinkError.
The details of the error are com.google.gwt.user.client.rpc.impl.ClientSerializationStreamReader.eval(Ljava/lang/String;)Lcom/google/gwt/core/client/JavaScriptObject;.

The server-side service is getting called and the async callback is hitting the onFailure(...) method, which is where I'm getting the error.

Is this a client-side source problem? I have verified that gwt-user.jar and gwt-dev.jar are in the source classpath on the DevMode launch configuration. I have single-stepped through the app and can't see where it's failing.