Larry,
Managed to find the problem.
I have an Optional Section that contains some textbox controls and I also had a Ink Picture control. I wanted the Ink Picture to be quite large so I put it and a textbox into a new Section inside the Optional Section and placed a button and hidden textbox just outside the new Section (but still in the Optional Section). I put some rules in place on the button click to set the value of the hidden textbox and rules on the new Section to show or hide depending on the hidden textbox value.
When the form loads initially I have a link to add a new "Optional Section" and when this is clicked the Optional Section is added along with its controls, including the button and new Section with the Ink Picture and textbox.
If I click the button to hide the new Section with the Ink Picture and textbox it hides fine.
If I click the button again the new Section shows and textbox is shown but the Ink Picture doesn't show. It looks as if the Ink Picture is not being loaded correctly as the Ink Picture toolbar option is displayed.
If I change the Optional Section to a normal Section the functionality works fine but as I need to have the Optional Section the only way around this is to move the button and hidden textbox outside the Optional Section.
As a result of this I have to hide the button if the Optional Section is not present.
Anyway this is my work-around. If you understand what the initial problem is and know of a better way to solve this please let me know.
Cheers.