Deleting Page messes up widgets

I am using a theme which relies solely on widgets.

When I delete a page it is messing up the existing widgets – some are ‘lost’ and don’t appear whereas other still appear.

Looking at the wp_options table I can’t see any change pre and post page deletion.

So why is there a problem and is there a ‘fix’ to correct this please?

Thanks
Mark

PS – I know the simple solution is not to delete pages but set the page status to “Pending Review” or “Draft”. However this can leave a messy list of obsolete pages.