I had some trouble with a WebForm, including a OleDbDataAdapter, a DataSet and uses the OleDbCommandBuilder to publish the CommandText property to the DataAdapter, that tries to update five Decimal columns in a Access database. No matter what I did, the Update method of the DataAdapter threw a DBConcurrencyException. After googling a few minutes I found someting about the ODBC/JET data type limit.

So I changed the Decimal to a Double and now all works fine.