Thanks for reply. I have answered next to your questions below.
What is the text of the error?
What Version of DW are you using?
What is your OS?
What extensions, including the version numbers are installed?
Design extender 1.1.3
Please provide the steps you are following to produce the error.
I am using the insert menu/Form/Text to insert a text field in a form.
The same problem occurs if I try to insert a Text area or a Fieldset but not if I insert a Date or Color field.
Hope this will give you the correct information.