com.atlassian.crowd.embedded.atlassianuser.EmbeddedCrowdUser cannot be cast to com.atlassian.confluence.user.ConfluenceUser

I have upgraded confluence 5.1.5 to 5.2.3 version. After upgraded successfully, i try to surf the page and it return 500 error with exception:

java.lang.ClassCastException: com.atlassian.crowd.embedded.atlassianuser.EmbeddedCrowdUser cannot be cast to com.atlassian.confluence.user.ConfluenceUser at com.atlassian.confluence.user.AuthenticatedUserThreadLocal.get(AuthenticatedUserThreadLocal.java:39)

when i hit enter at url again it backs to normal. Is this version affect the custom authenticator(custauth-1.0.jar) behavior?
I am using ntlm login connector for my site.