I installed the Selenium Grid plugin and launched a slave on my Ubuntu 9.10 desktop via JNLP. It shows up in the Selenium Grid section of Hudson as the 1 RC instance.

I then attempted to plug either the IP/port of the RC in directly to our tests, or the Hudson address with port 4444 as the grid. In either case I end up with:

18:16:08.087 INFO - Command request: getNewBrowserSession[*firefox3, https://mysite/] on session null
18:16:08.087 INFO - creating new remote session
18:16:08.088 INFO - Allocated session 0f827a53bb4b434a9b4dfb9f7d0c0a7b for https://mysite/, launching...
18:16:08.130 ERROR - Failed to start new browser session, shutdown browser and clear all session data
java.lang.NullPointerException
at java.io.FilterInputStream.read(FilterInputStream.java:116)
at java.io.FilterInputStream.read(FilterInputStream.java:90)
at hudson.remoting.RemoteClassLoader$ClassLoaderProxy.readFully(RemoteClassLoader.java:311)
at hudson.remoting.RemoteClassLoader$ClassLoaderProxy.getResource(RemoteClassLoader.java:292)
at sun.reflect.GeneratedMethodAccessor348.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at hudson.remoting.RemoteInvocationHandler$RPCRequest.perform(RemoteInvocationHandler.java:274)
at hudson.remoting.Request$2.run(Request.java:270)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:441)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
at java.util.concurrent.FutureTask.run(FutureTask.java:138)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:885)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:907)
at java.lang.Thread.run(Thread.java:619)
18:16:08.131 INFO - Got result: Failed to start new browser session: Error while launching browser on session null

If I just download Selenium RC 1.0.1 from the website and launch the JAR on my Ubuntu desktop and use my IP with port 4444, everything works fine. But then changing it back to the port Hudson gave it (or the grid address) results in the above error.

Any suggestions?