ClassCastException on RSS feeds

For this feed:

http://extranet.atlassian.com/createrssfeed.action?types=page&types=blogpost&types=mail&types=comment&types=attachment&statuses=created&statuses=modified&spaces=SALES&labelString=&rssType=rss2&maxResults=10&timeSpan=5&publicFeed=false&title=Extranet+Sales+Feed&os_authType=basic

I get this error:

System Error

A system error has occurred - our apologies!
Please create a support issue on our support system at http://support.atlassian.com with the following information:

a description of your problem and what you were doing at the time it occurred
cut & paste the error and system information found below
attach the application server log file (if possible).
We will respond as promptly as possible.
Thank you!
Cause:
java.lang.ClassCastException
at com.atlassian.confluence.rss.AttachmentRenderSupport.getCategories(AttachmentRenderSupport.java:52)
at com.atlassian.confluence.rss.DefaultFeedBuilder.createFeed(DefaultFeedBuilder.java:63)
at sun.reflect.GeneratedMethodAccessor948.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:324)
at org.springframework.aop.framework.AopProxyUtils.invokeJoinpointUsingReflection(AopProxyUtils.java:61)
at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:149)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:116)
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:56)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:138)
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:152)
at $Proxy23.createFeed(Unknown Source)
at com.atlassian.confluence.spaces.actions.CreateRssFeedAction.getSyndFeed(CreateRssFeedAction.java:42)
at sun.reflect.GeneratedMethodAccessor947.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:324)
at ognl.OgnlRuntime.invokeMethod(OgnlRuntime.java:491)
at ognl.OgnlRuntime.getMethodValue(OgnlRuntime.java:904)
at ognl.ObjectPropertyAccessor.getPossibleProperty(ObjectPropertyAccessor.java:54)
at ognl.ObjectPropertyAccessor.getProperty(ObjectPropertyAccessor.java:122)
at ognl.OgnlRuntime.getProperty(OgnlRuntime.java:1616)
at com.opensymphony.xwork.util.CompoundRootAccessor.getProperty(CompoundRootAccessor.java:97)
at ognl.OgnlRuntime.getProperty(OgnlRuntime.java:1616)
at ognl.ASTProperty.getValueBody(ASTProperty.java:96)
at ognl.SimpleNode.evaluateGetValueBody(SimpleNode.java:171)
at ognl.SimpleNode.getValue(SimpleNode.java:193)
at ognl.Ognl.getValue(Ognl.java:333)
at ognl.Ognl.getValue(Ognl.java:310)
at com.opensymphony.xwork.util.OgnlValueStack.findValue(OgnlValueStack.java:141)
at com.atlassian.confluence.core.actions.RssResult.doExecute(RssResult.java:34)
at com.opensymphony.webwork.dispatcher.WebWorkResultSupport.execute(WebWorkResultSupport.java:116)
at com.opensymphony.xwork.DefaultActionInvocation.executeResult(DefaultActionInvocation.java:263)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:187)
at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:35)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:165)
at com.atlassian.confluence.security.actions.PermissionCheckInterceptor.intercept(PermissionCheckInterceptor.java:40)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:165)
at com.atlassian.confluence.pages.actions.PageAwareInterceptor.intercept(PageAwareInterceptor.java:94)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:165)
at com.atlassian.confluence.spaces.actions.SpaceAwareInterceptor.intercept(SpaceAwareInterceptor.java:82)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:165)
at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:35)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:165)
at com.atlassian.confluence.core.ConfluenceAutowireInterceptor.intercept(ConfluenceAutowireInterceptor.java:25)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:165)
at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:35)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:165)
at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:35)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:165)
at com.atlassian.confluence.util.XWorkTransactionInterceptor.intercept(XWorkTransactionInterceptor.java:133)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:165)
at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:35)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:165)
at com.opensymphony.xwork.DefaultActionProxy.execute(DefaultActionProxy.java:115)
at com.opensymphony.webwork.dispatcher.ServletDispatcher.serviceAction(ServletDispatcher.java:229)
at com.opensymphony.webwork.dispatcher.ServletDispatcher.service(ServletDispatcher.java:199)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:103)
at com.caucho.server.http.FilterChainServlet.doFilter(FilterChainServlet.java:96)
at com.opensymphony.module.sitemesh.filter.PageFilter.parsePage(PageFilter.java:118)
at com.atlassian.confluence.util.profiling.ProfilingPageFilter.parsePage(ProfilingPageFilter.java:150)
at com.opensymphony.module.sitemesh.filter.PageFilter.doFilter(PageFilter.java:52)
at com.caucho.server.http.FilterChainFilter.doFilter(FilterChainFilter.java:88)
at com.atlassian.confluence.util.UserThreadLocalFilter.doFilter(UserThreadLocalFilter.java:46)
at com.caucho.server.http.FilterChainFilter.doFilter(FilterChainFilter.java:88)
at com.atlassian.seraph.filter.SecurityFilter.doFilter(SecurityFilter.java:182)
at com.caucho.server.http.FilterChainFilter.doFilter(FilterChainFilter.java:88)
at com.atlassian.seraph.filter.LoginFilter.doFilter(LoginFilter.java:177)
at com.caucho.server.http.FilterChainFilter.doFilter(FilterChainFilter.java:88)
at com.atlassian.johnson.filters.JohnsonFilter.doFilter(JohnsonFilter.java:96)
at com.caucho.server.http.FilterChainFilter.doFilter(FilterChainFilter.java:88)
at org.springframework.orm.hibernate.support.OpenSessionInViewFilter.doFilterInternal(OpenSessionInViewFilter.java:170)
at bucket.custom.FlushingSpringSessionInViewFilter.doFilterInternal(FlushingSpringSessionInViewFilter.java:31)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:73)
at com.caucho.server.http.FilterChainFilter.doFilter(FilterChainFilter.java:88)
at com.atlassian.util.profiling.filters.ProfilingFilter.doFilter(ProfilingFilter.java:132)
at com.atlassian.confluence.util.error.ProfilingAndErrorFilter.doFilter(ProfilingAndErrorFilter.java:27)
at com.caucho.server.http.FilterChainFilter.doFilter(FilterChainFilter.java:88)
at com.atlassian.core.filters.gzip.GzipFilter.doFilter(GzipFilter.java:61)
at com.caucho.server.http.FilterChainFilter.doFilter(FilterChainFilter.java:88)
at com.atlassian.core.filters.AbstractEncodingFilter.doFilter(AbstractEncodingFilter.java:37)
at com.caucho.server.http.FilterChainFilter.doFilter(FilterChainFilter.java:88)
at com.caucho.server.http.Invocation.service(Invocation.java:315)
at com.caucho.server.http.HttpRequest.handleRequest(HttpRequest.java:246)
at com.caucho.server.http.HttpRequest.handleConnection(HttpRequest.java:163)
at com.caucho.server.TcpConnection.run(TcpConnection.java:139)
at java.lang.Thread.run(Thread.java:534)

Although I love the fact that I get the error in the RSS feed - that is brilliant!