Broken uvs

Blender 2.77
Win 10 64 bit

Unwarap mesh and go to move a uv island in the uv view (editor) and it leaves polys behind. Seems edges that are not marked as seams and are properly connected to the mesh are broken after unwrap. Any help on this would be appreciated.

Any help on this would be appreciated.
Any demo blend file to review would be appreciated