Yes thanks Derek, I do have both ticked, it is so annoying when it happens because most of the date pickers are 'not visible'. Maybe that is the problem as it doesn't seem to happen so much with the visible date pickers.
The inexplicable moving of buttons and edit boxes is more of a pain though. It only happens with the components placed on the page control. I think the problem might be as the form is saved some corruption happens which changes the right and bottom settings of the page in the XML file, and as the page control is not resizeable once laid out it makes it appear that components have moved.
In fact I've just checked using XML Notepad the page control dimensions have changed between savings.
On a clear disk you can seek forever