CXF - ClassCastException (SEIStub/ClientProxy)

I'm trying to build a client jar file to access a webservice. I'm including the jar in a servlet/war that makes the client webservice calls. I'm getting the following error:

INFO: 2011 Apr 14 14:57:32,780 MDT [http-thread-pool-8181(4)] ERROR     my.package.ClientServlet - Caught exception
java.lang.ClassCastException: com.sun.xml.ws.client.sei.SEIStub cannot be cast to org.apache.cxf.frontend.ClientProxy
at org.apache.cxf.frontend.ClientProxy.getClient(ClientProxy.java:93)
at my.package.Client.(Client.java:54)
at my.package.ClientServlet.testService(TestServlet.java:118)

I came across this post http://yaytay.wordpress.com/2010/03/06/lsned-29-persuading-jdk-6-to-use-cxf-classes-rather-than-its-own-avoiding-seistub/ which says to fix the problem you need to include cxf-rt-frontend-jaxws as a dependency, which I do. So, that isn't the problem/solution in my case.

My client jar pom has these dependencies:

    2.3.3


    
        org.apache.cxf
        cxf-rt-frontend-jaxws
        ${cxf.version}
    
    
        org.apache.cxf
        cxf-rt-ws-security
        ${cxf.version}
    

The servlet war contains the following in its lib:

asm-3.3.jar
bcprov-jdk15-1.45.jar
commons-logging-1.1.1.jar
cxf-api-2.3.3.jar
cxf-common-schemas-2.3.3.jar
cxf-common-utilities-2.3.3.jar
cxf-rt-bindings-soap-2.3.3.jar
cxf-rt-bindings-xml-2.3.3.jar
cxf-rt-core-2.3.3.jar
cxf-rt-databinding-jaxb-2.3.3.jar
cxf-rt-frontend-jaxws-2.3.3.jar
cxf-rt-frontend-simple-2.3.3.jar
cxf-rt-ws-addr-2.3.3.jar
cxf-rt-ws-security-2.3.3.jar
cxf-tools-common-2.3.3.jar
geronimo-javamail_1.4_spec-1.7.1.jar
jaxb-impl-2.1.13.jar
log4j-1.2.14.jar
neethi-2.0.4.jar
my-client-cxf-1.0.jar
serializer-2.7.1.jar
slf4j-api-1.4.2.jar
slf4j-log4j12-1.4.2.jar
stax2-api-3.0.2.jar
woodstox-core-asl-4.0.8.jar
wsdl4j-1.6.2.jar
wss4j-1.5.11.jar
xalan-2.7.1.jar
xml-resolver-1.2.jar
XmlSchema-1.4.7.jar
xmlsec-1.4.4.jar

I've also read some posts that talk about a javax.xml.ws.spi.Provider file, but haven't been able to find any references that detail what it should be named, contain and placed.

Can anybody point me in the right direction?