Widgets don't work consistently

This problem has been occurring for some time now.
PROBLEM:
I can’t drag/drop widgets into sidebar areas. The drop down arrows on the sidebars don’t actually open a widget placed there. When I click on a widget in the sidebar, the browser screen scrolls up to where my mouse was but doesn’t actually open the widget.

WHAT I’VE TRIED:

• Deactivated all plugins – no change
• Added define( ‘CONCATENATE_SCRIPTS’, false ); to wp-config – no change BUT! when I removed the “define….” code from wp-config, and refreshed my page, the widgets worked again and I was able to drag/drop widgets to the sidebars and the widgets in the sidebars allowed me to click on the drop down and access them.

BUT! (again) when I left the Widgets page and navigated to any other section of the admin area and went back to the Widgets page, the problem was back e.g., Can’t move or open widgets at all.

Any ideas what’s happening here? It’s really frustrating not to be able to work in the Widgets area with any consistency.

THANK YOU!