Damn dirty databinding - why is CurrencyManager.Position changing???

I have a form containing various controls bound to columns in a dataset.
The table these fields are bound to has only 1 record in it. When I
explicitly change a value in the table the bound controls are clearing and I
believe it's because the position of the default currency manager is
changing. I cannot figure out why it is changing but it is causing problems
with code that has existed error-free for over a year now. Yeah, I know
that is a ludicrous statement - something has had to change but I can't
figure out what would cause this issue. To further complicate the issue it
only happens with some records and they appear no different from records for
which the code works.

How could performing the following action cause the currency manager
position to change????? It appears to change when the implicit call to
EndEdit is occurring. (I've added BeginEdit and EndEdit calls around the
following code to debug it and the currency manager position is changing
when EndEdit is called.)

MyDataSet.MyTable(0).TotalSale = 0

Thanks in advance for any help!