When running a Maven2 job on a slave instance, I get the following message (complete stack trace attached): "java.lang.ClassNotFoundException: Classloading from system classloader disabled". This happens with the first job after the slave instance is started (it's running as a Windows service). After that, I get a "java.lang.NoClassDefFoundError: Could not initialize class hudson.maven.MavenModuleSetBuild" error.
If I create a freestyle job, and include the maven command as a batch command to run on the slave, it works fine. The Maven2 job appears to locate Maven on the slave machine, but it apparently can't find the maven-plugin (probably due to the classloading error).