Don:
OK. I can replicate the issue. I have a report that is pulling data from SQL Server using the OLEDB. There is a column in the data view called "HedgeGroup" and this column contains a few values of "<Select>". When you view the report in the web report viewer, omitting "HedgeGroup" from the details section, with 2 groups, "HedgeGroup" being the second group, the report displays without issue.
If you change "HedgeGroup" to be the first of the two groups, it fails. I've been able to predictably replicate this several times. It might be due to the fact that when "HedgeGroup" is the first group, it causes the value "<Select>" to be displayed in then treeview section. I realize this is a very strange issue, if you want to setup a web meeting to see this, let me know. Eric Ocampo at SAP has my contact information.
Thanks,
Greg Ellis