Widget configuration goes blank

Hello,

I’ve written a plugin that installs multiple widgets and adds a plugin configuration menu to the backend.

Now, whenever I add any widget (one of mine or one of the widgets included by default) to a sidebar, the widget’s configuration form loads up and then disappears. However, once I click the “save” button, the form reappears and there are no problems ever again.

For example, if I drag the Tag Cloud widget to a sidebar, the “title” and “taxonomy” fields appear for half a second then disappear. I click “Save” and they reappear. I can then return to the widgets setup page any time and if I toggle the Tag Cloud widget in the sidebar, the fields are there and stay there.

What could be causing this?