Looking at SQL Server profiler output, in order to get the stored procedure parameter list, you reference a table "master.dbo.spt_provider_types" that is no more present in the latest pre-release of SQL Server 2005 (June CTP).
Yesterday I was in Microsoft Italia and they confirmed that the above table is removed, since it was an undocumented feature.
We tried to work with database in compatibility mode 80 but it did not work because you reference a master table.
Please, let me know if you need more detail to reproduce the problem.
Thanks.