Repeatable loss of functionality with specific plugins

I am experiencing the issues below when I use:

TwitterTools
wp-Invoice

Issue 1:
When trying to insert an image into a post or a page I no longer get the popup window with the grey background, however I do get a full web page with the insert image options and buttons, but this is unusable.
Issue 2:
I lose all drag and drop functionality within the dashboard.

If I disable these plugins everything reverts back to normal.

I’ve seen several postings on these forums where this has been an issue for many, but no clear resolution.

I run a Blog hosting service for hundreds of people and this problem is common to all of them, even on brand new virgin WordPress installations.