I am experiencing a strange behavior when reading a resultset from database in a calling method. The sort of the rows is different from what the database should return.

My farm:
- database server: sql server 2008 on a WinServer 2008 64 bit
- web server: a couple of load balanced WinServer 2008 64 bit running IIS 7
The application runs on a v4.0 app pool, set to enable 32bit applications

Here's a description of the problem:
- a stored procedure is called, that returns a resultset sorted on a particular column
- I can see thru profiler the call to the SP, if I run the statement I see correct sorting
- the calling page gets the results, and before any further elaboration logs the rows immediately after the SP execution
- the results are in a completely different order (I cannot even understand if they are sorted in any way)

Some details on the Stored Procedure:
- it is called by code using a SqlDatAdapter
- it has also an output value (a count of the rows) that is read correctly
- which sort field is to be used is passed as a parameter - makes use of temp tables to collect data and perform the desired sort

Any idea on what I could check? Same code and same database work correctly in a test environment, 32 bit and not load balanced.