GridView - losing controls

I have an autogenerated GridView.
I examine the first row of data and construct a set of edit boxes(if the
Cell's control collection is empty a TextBox, if not, examine the control (in
practice always a CheckBox)and reproduce it in the edit line. This works fine.

Now (today, not yesterday) if I select a row I can populate the edit boxes
by copying them from the row selected, or, if the cell has a control (always
a CheckBox) copy its Checked property. Yesterday this worked fine.
Today, none of the Cells have a Control and hence this fails. However each
row in the GridView has ***exactly*** twice the number of cells that it
should have!(the second set all have Text = "")

wtf is going on?

Guy