Crystal Reports XI: Money values appear as “Zeros”

We have a problem using Crystal Reports XI, VB and .NET 1.1 whereby a Report returning money values will return just 0.00 instead of the actual value held on the database. Database is Ingres 2.6 accessed via Ingres ODBC, but our tests show that the correct values are returned via the ODBC.
To make it worse, the same report DOES return the correct values on some Win XP Pro workstations and W2K3 Servers, eg. it works correctly on one of our 2 Metaframe Servers, but not on the other.
Has anyone seen this problem before, or have suggestions as to what causes it?
Many Thanks, Phil