Hudson web interface is unviewable (encoding error) when Release plugin is enabled

Using Hudson 1.333

With the release plugin enabled (version 1.8), I get a content encoding error
when I try to view Hudson. When the release plugin is disabled, I can load and
interact with Hudson in my browser.

When the release plugin is enabled, there are a lot of exceptions that start
with a failure to load the release plugin.

WARNING: Failed to load a project
java.lang.NoClassDefFoundError:
hudson/plugins/release/dashboard/RecentReleasesPortlet
at java.lang.Class.getDeclaringClass(Native Method)
at java.lang.Class.getEnclosingClass(Class.java:1102)
at hudson.model.Descriptor.<init>(Descriptor.java:216)
at
hudson.plugins.release.dashboard.RecentReleasesPortlet$DescriptorImpl.<init>(RecentReleasesPortlet.java:118)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at
sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
at
sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)

And when it tries to start one of my slaves:

Nov 12, 2009 10:37:10 AM hudson.ExpressionFactory2$JexlExpression evaluate
WARNING: Caught exception evaluating: it.statData. Reason:
java.lang.reflect.InvocationTargetException
java.lang.reflect.InvocationTargetException
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:616)
at org.apache.commons.jexl.util.PropertyExecutor.execute(PropertyExecutor.java:125)
at
org.apache.commons.jexl.util.introspection.UberspectImpl$VelGetterImpl.invoke(UberspectImpl.java:314)

It's not clear to me whether (or why) the release plugin failure is related to
these other failures, but disabling the release plugin makes these failures go away.