Why can’t I view or use the Library Manager page/Approval Gallery/Lightbox?

This is most likely a Flash-related issue. There are a few ways to solve this:

• Reset UI by going to Settings at the top right corner. 
• If this problem still exists, then update to current Flash version and check that your machine is meeting minimum system tech requirements. A good site to check if your computer meets our minimum requirements is www.supportdetails.com. 
• Finally, if you are still experiencing this issue, reset the Flash cache by right-clicking on an image and hit Global Settings.  Select Delete All. 

More about Flash and UI:

GLOBALedit Minimum Requirements / Tech Specs