Refresh SQL Server Native Client after renaming a Field?

Hello,

I renamed a Field of a FeatureClass in an ArcSDE with the IClassSchemaEdit4.AlterFieldName Method.
This works fine, but as soon as I create a Cursor to iterate the FeatureClass I get an SQL Server Native Client Error, which can't find the old(!!) Fieldname in the Database.
But if i look for the renamed Field in the FeatureClass everything is fine --> I can't find the old fieldname and the new one is there.

I have no idea why the Native Client is looking for the old Fieldname? Do I have to refresh the Client somehow?

If I restart my application or look at the FeatureClass with ArcCatalog everything works fine.

Any idea whats going on with the Microsoft SQL Server Native Client 10.0?

Thanks
Mickey