Log4j error at JBoss startup time: class path contains multiple SLF4J bindings.

I installed JBoss AS 5.1.0.GA and deploying ESB and Riftsaw (including updating the web service stack). When JBoss is started, a set of error messages appear in the log about not being able to instantiate an object due to multiple bindings of the same (or sufficiently similar) class present in the classpath.

The relevant section of the log is pasted below for consultation.

16:17:22,506 INFO [TomcatDeployment] deploy, ctxPath=/bpel-console
16:17:23,064 ERROR [STDERR] SLF4J: Class path contains multiple SLF4J bindings.
16:17:23,064 ERROR [STDERR] SLF4J: Found binding in [vfszip:/home/max/redhat/jboss-5.1.0.GA/common/lib/slf4j-jboss-logging.jar/org/slf4j/impl/StaticLoggerBinder.class]
16:17:23,064 ERROR [STDERR] SLF4J: Found binding in [vfszip:/home/max/redhat/jboss-5.1.0.GA/server/default/deploy/bpel-console/gwt-console.war/WEB-INF/lib/slf4j-log4j12-1.5.10.jar/org/slf4j/impl/StaticLoggerBinder.class]
16:17:23,064 ERROR [STDERR] SLF4J: See http://www.slf4j.org/codes.html#multiple_bindings for an explanation.
16:17:23,115 ERROR [STDERR] log4j:ERROR A "org.jboss.logging.appender.FileAppender" object is not assignable to a "org.apache.log4j.Appender" variable.
16:17:23,115 ERROR [STDERR] log4j:ERROR The class "org.apache.log4j.Appender" was loaded by
16:17:23,115 ERROR [STDERR] log4j:ERROR [BaseClassLoader@f56489

] whereas object of type
16:17:23,119 ERROR [STDERR] log4j:ERROR "org.jboss.logging.appender.FileAppender" was loaded by [org.jboss.bootstrap.NoAnnotationURLClassLoader@1d8957f].
16:17:23,119 ERROR [STDERR] log4j:ERROR Could not instantiate appender named "FILE".