After upgrading our report server from SQL2008 to SQL2008 R2, one of our complex production reports will no longer work properly. This report has several parameters such as selecting all data or a specific group of data, and selecting summary data only or detail along with the summary. Since going to R2, if we select a small group detail report, it will produce only the first detail page and then the summary page rather than all the detail pages then the summary page. If we select all data, the report never finishes - it will show LOADING.... forever. When I load this report onto a SQL2008 non R2 report sever, running this report for all data takes about 10 seconds. Running it for a small group shows the 10 detail pages and then the final summary page. Right now, running this report on a non R2 SQL 2008 server is my work around.