Yes, I'd figured that you meant collections, not containers.

Now, I'm just guessing about all this, because you didn't post any of
the relevant code, but I suspect that you loaded up your collection from
a recordset that you'd opened on a table, using code something like
this:

   Dim foo As Collection

   ' ...
   Dim rs As DAO.Recordset   ' or could be ADODB.Recordset

   Set foo = New Collection
   Set rs = CurrentDb.OpenRecordset("Bar")

   Do Until rs.EOF
       foo.Add rs!SomeField
       rs.MoveNext
   Loop

   rs.Close
   Set rs = Nothing

Now remember that a Collection can hold objects, not just simple types.
The way the above code is written, what is actually stored in the
collection foo is *not* the value of SomeField for each record in rs;
instead, what is stored there are multiple objects of type Field, with
all the properties of a Field object.  However, each of those Field
objects is dependent on the parent recordset rs to which it belongs.  In
fact, closer examination would show that, at any given time, the Value
properties of all the field objects in foo are the same -- the value of
SomeField in the current record of rs.  When rs is closed, though, those
Field objects are no longer valid.  If you try to dereference any member
of the collection at this point, you'll get error 3420: Object invalid
or no longer set.

If you want to store the *values* of SomeField, from all the records in
rs, in the collection, you have to specify that specifically when adding
the item to the collection:

       foo.Add rs!SomeField.Value

That way, what gets stored in the collection is not the field itself,
but the result of evaluating its Value property.