Recently we posted an article on : http://blogs.msdn.com/b/selvar/archive/2011/05/01/report-builder-3-0-stops-responding-after-you-run-a-query-more-than-two-times-against-a-report-model-when-authentication-mode-for-reporting-service-2008-r2-is-set-for-basic-or-custom-authentication.aspx

HTH!

Reporting Service India Support Team.

[All the posts are AS - IS and doesn't carry any warranty]