Ouch.
Same problem on Windows XP SP3, Hudson 1.349, Subversion Plugin 1.12. Running on JDK 1.6.0_18 and using built-in servlet container.
Started on Mar 8, 2010 12:16:27 PM
ERROR: Failed to record SCM polling
[8mha:AAAAVx+LCAAAAAAAAABb85aBtbiIQSmjNKU4P08vOT+vOD8nVc8DzHWtSE4tKMnMz/PLL0m1W6NqK7pC2JmJgaGiiEEKTYMzhAYpZIAARpDCAgBF2FTYYAAAAA==[0mjava.lang.ClassCastException: hudson.scm.SCMRevisionState$None cannot be cast to hudson.scm.SVNRevisionState
at hudson.scm.SubversionSCM.compareRemoteRevisionWith(SubversionSCM.java:1051)
at hudson.scm.SCM.poll(SCM.java:342)
at hudson.model.AbstractProject.poll(AbstractProject.java:1162)
at hudson.triggers.SCMTrigger$Runner.runPolling(SCMTrigger.java:319)
at hudson.triggers.SCMTrigger$Runner.run(SCMTrigger.java:348)
at hudson.util.SequentialExecutionQueue$QueueEntry.run(SequentialExecutionQueue.java:118)
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$Worker.runTask(ThreadPoolExecutor.java:886)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
at java.lang.Thread.run(Thread.java:619)
I've seen the same problem. Reverting to the Subversion plugin 1.11 fixes the problem.